fossat

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Author name code: fossat
ADS astronomy entries on 2022-09-14
author:"Fossat, Eric"

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Title: Dome C coherence time statistics from DIMM data
Authors: Aristidi, E.; Agabi, A.; Abe, L.; Fossat, E.; Ziad, A.;
Mékarnia, D.
2020MNRAS.496.4822A Altcode: 2020MNRAS.tmp.1986A; 2020arXiv200613778A
We present a reanalysis of several years of DIMM data at the site
of Dome C, Antarctica, to provide measurements of the coherence time
τ0. Statistics and seasonal behaviour of τ0 are
given at two heights above the ground, 3 and 8 m, for the wavelength λ
= 500 nm. We found an annual median value of 2.9 ms at the height of
8 m. A few measurements could also be obtained at the height of 20 m
and give a median value of 6 ms during the period June-September. For
the first time, we provide measurements of τ0 in daytime
during the summer, which appears to show the same time dependence as
the seeing with a sharp maximum at 5 PM local time. Exceptional values
of τ0 above 10 ms are met at this particular moment. The
continuous slow variations of turbulence conditions during the day
offers a natural test bed for a solar adaptive optics system.

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Title: More about solar g modes
Authors: Fossat, E.; Schmider, F. X.
2018A&A...612L...1F Altcode:
Context. The detection of asymptotic solar g-mode parameters
was the main goal of the GOLF instrument onboard the SOHO space
observatory. This detection has recently been reported and has
identified a rapid mean rotation of the solar core, with a one-week
period, nearly four times faster than all the rest of the solar
body, from the surface to the bottom of the radiative zone. Aim. We
present here the detection of more g modes of higher degree, and a
more precise estimation of all their parameters, which will have to be
exploited as additional constraints in modeling the solar core. 
Methods: Having identified the period equidistance and the splitting
of a large number of asymptotic g modes of degrees 1 and 2, we test a
model of frequencies of these modes by a cross-correlation with the
power spectrum from which they have been detected. It shows a high
correlation peak at lag zero, showing that the model is hidden but
present in the real spectrum. The model parameters can then be adjusted
to optimize the position (at exactly zero lag) and the height of this
correlation peak. The same method is then extended to the search for
modes of degrees 3 and 4, which were not detected in the previous
analysis. Results: g-mode parameters are optimally measured
in similar-frequency bandwidths, ranging from 7 to 8 μHz at one
end and all close to 30 μHz at the other end, for the degrees 1 to
4. They include the four asymptotic period equidistances, the slight
departure from equidistance of the detected periods for l = 1 and l =
2, the measured amplitudes, functions of the degree and the tesseral
order, and the splittings that will possibly constrain the estimated
sharpness of the transition between the one-week mean rotation of the
core and the almost four-week rotation of the radiative envelope. The
g-mode periods themselves are crucial inputs in the solar core structure
helioseismic investigation.

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Title: Detection of g modes in the asymptotic frequency range:
evidence for a rapidly rotating core
Authors: Ulrich, Roger K.; Fossat, Eric; Boumier, Patrick; Corbard,
Thierry; Provost, Janine; Salabert, David; Schmider, François-Xavier;
Gabriel, Alan; Grec, Gerard; Renaud, Catherine; Robillot, Jean-Maurice;
Roca Cortés, Teodoro; Turck-Chièze, Sylvaine
2017SPD....4810906U Altcode:
We present the identification of very low frequency g modes, in the
asymptotic regime, and two important parameters: the core rotation rate
and the asymptotic equidistant period spacing of these g modes. The
GOLF instrument on the SOHO space observatory has provided two
decades of full disk helioseismic data. The search for g modes in
GOLF measurements has been extremely difficult, due to solar and
instrumental noise. In the present study, the p modes of the GOLF
signal are analyzed differently, searching for possible collective
frequency modulations produced by periodic changes in the deep solar
structure. Such modulations provide access to only very low frequency
g modes, thus allowing statistical methods to take advantage of their
asymptotic properties. For oscillatory periods in the range between 9
and nearly 48 hours, almost 100 g modes of spherical harmonic degree
1 and more than 100 g modes of degree 2 are predicted. They are not
observed individually, but when combined, they unambiguously provide
their asymptotic period equidistance and rotational splittings,
in excellent agreement with the requirements of the asymptotic
approximations. P0, the g-mode period equidistance parameter, is
measured to be 34 min 01 s, with a 1 s uncertainty. The previously
unknown g-mode splittings have now been measured from a non synodic
reference with a very high accuracy, and they imply a mean weighted
rotation of 1277 ± 10 nHz (9-day period) of their kernels, resulting
in a rapid rotation frequency of 1644 ± 23 nHz (period of one week)
of the solar core itself, which is a factor 3:8 ± 0:1 faster than the
rotation of the radiative envelope.Acknowledgements. Ulrich is first
author on this abstract due to AAS rules, Fossat is the actual first
author. SOHO is a project of international collaboration between ESA and
NASA. We would like to acknowledge the support received continuously
during more than 3 decades from CNES. DS acknowledges the financial
support from the CNES GOLF grant and the Observatoire de la Côte
d’Azur for support during his stays. RKU acknowledges support from
NASA for his participation in this project and thanks John Bahcall
for enthusiastic encouragement for the g-mode search.

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Title: Asymptotic g modes: Evidence for a rapid rotation of the
solar core
Authors: Fossat, E.; Boumier, P.; Corbard, T.; Provost, J.; Salabert,
D.; Schmider, F. X.; Gabriel, A. H.; Grec, G.; Renaud, C.; Robillot,
J. M.; Roca-Cortés, T.; Turck-Chièze, S.; Ulrich, R. K.; Lazrek, M.
2017A&A...604A..40F Altcode: 2017arXiv170800259F
Context. Over the past 40 years, helioseismology has been enormously
successful in the study of the solar interior. A shortcoming has
been the lack of a convincing detection of the solar g modes, which
are oscillations driven by gravity and are hidden in the deepest
part of the solar body - its hydrogen-burning core. The detection
of g modes is expected to dramatically improve our ability to model
this core, the rotational characteristics of which have, until now,
remained unknown. Aims: We present the identification of very
low frequency g modes in the asymptotic regime and two important
parameters that have long been waited for: the core rotation rate,
and the asymptotic equidistant period spacing of these g modes. 
Methods: The GOLF instrument on board the SOHO space observatory has
provided two decades of full-disk helioseismic data. The search for
g modes in GOLF measurements has been extremely difficult because of
solar and instrumental noise. In the present study, the p modes of the
GOLF signal are analyzed differently: we search for possible collective
frequency modulations that are produced by periodic changes in the
deep solar structure. Such modulations provide access to only very low
frequency g modes, thus allowing statistical methods to take advantage
of their asymptotic properties. Results: For oscillatory
periods in the range between 9 and nearly 48 h, almost 100 g modes
of spherical harmonic degree 1 and more than 100 g modes of degree 2
are predicted. They are not observed individually, but when combined,
they unambiguously provide their asymptotic period equidistance and
rotational splittings, in excellent agreement with the requirements
of the asymptotic approximations. When the period equidistance has
been measured, all of the individual frequencies of each mode can
be determined. Previously, p-mode helioseismology allowed the g-mode
period equidistance parameter P0 to be bracketed inside a
narrow range, between approximately 34 and 35 min. Here, P0
is measured to be 34 min 01 s, with a 1 s uncertainty. The previously
unknown g-mode splittings have now been measured from a non-synodic
reference with very high accuracy, and they imply a mean weighted
rotation of 1277 ± 10 nHz (9-day period) of their kernels, resulting
in a rapid rotation frequency of 1644 ± 23 nHz (period of one week)
of the solar core itself, which is a factor 3.8 ± 0.1 faster than the
rotation of the radiative envelope. Conclusions: The g modes
are known to be the keys to a better understanding of the structure
and dynamics of the solar core. Their detection with these precise
parameters will certainly stimulate a new era of research in this field.

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Title: Monitoring the optical turbulence in the surface layer at
Dome C, Antarctica, with sonic anemometers
Authors: Aristidi, E.; Vernin, J.; Fossat, E.; Schmider, F. -X.;
Travouillon, T.; Pouzenc, C.; Traullé, O.; Genthon, C.; Agabi, A.;
Bondoux, E.; Challita, Z.; Mékarnia, D.; Jeanneaux, F.; Bouchez, G.
2015MNRAS.454.4304A Altcode: 2018arXiv181107585A
The optical turbulence above Dome C in winter is mainly concentrated in
the first tens of metres above the ground. Properties of this so-called
surface layer (SL) were investigated during the period 2007-2012 by
a set of sonic anemometers placed on a 45 m high tower. We present
the results of this long-term monitoring of the refractive index
structure constant C_n^2 within the SL, and confirm its thickness of
35 m. We give statistics of the contribution of the SL to the seeing
and coherence time. We also investigate properties of large-scale
structure functions of the temperature and show evidence of a second
inertial zone at kilometric spatial scales.

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Title: Study of the sub-AU disk of the Herbig B[e] star HD 85567
with near-infrared interferometry
Authors: Vural, J.; Kraus, S.; Kreplin, A.; Weigelt, G.; Fossat, E.;
Massi, F.; Perraut, K.; Vakili, F.
2014A&A...569A..25V Altcode: 2014arXiv1407.8190V
Context. The structure of the inner disk of Herbig Be stars is not
well understood. The continuum disks of several Herbig Be stars have
inner radii that are smaller than predicted by models of irradiated
disks with optically thin holes. Aims: We study the size of
the inner disk of the Herbig B[e] star HD 85567 and compare the model
radii with the radius suggested by the size-luminosity relation. Methods: The object was observed with the AMBER instrument of the
Very Large Telescope Interferometer. We obtained K-band visibilities
and closure phases. These measurements are interpreted with geometric
models and temperature-gradient models. Results: Using several
types of geometric star-disk and star-disk-halo models, we derived
inner ring-fit radii in the K band that are in the range of 0.8-1.6
AU. Additional temperature-gradient modeling resulted in an extended
disk with an inner radius of 0.67+0.51-0.21
AU, a high inner temperature of 2200+750-350 K,
and a disk inclination of 53+15-11 °. 
Conclusions: The derived geometric ring-fit radii are approximately 3-5
times smaller than that predicted by the size-luminosity relation. The
small geometric and temperature-gradient radii suggest optically thick
gaseous material that absorbs stellar radiation inside the dust disk. Based on observations made with ESO telescopes at the La Silla
Paranal Observatory under program IDs 080.C-0541(C), 082.C-0893(A),
084.C-0848(B).Appendix A is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201424214/olm">http://www.aanda.org</A>

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Title: Twenty-five years of helioseismology research in Uzbekistan
Authors: Ehgamberdiev, Sh. A.; Fossat, E.; Serebryanskiy, A. V.
2014JAHH...17...45E Altcode:
The Ulugh Beg Astronomical Institute was involved in the IRIS
helioseismology project from the mid-1980s through to the end of the
project in 2001. This project aimed to study the deep interior of the
Sun using Doppler spectral line shift measurements integrated over the
whole solar disk. In order to obtain long, continuous observational
data showing periodicity a network of six stations more or less
regularly distributed around the globe and equipped with identical
spectrophotometers was deployed. One of these instruments was installed
on Mt Kumbel in Uzbekistan in 1988. In addition, from 1996 to 2002
the Ulugh Beg Astronomical Institute was involved in observations
for the TON project, which was aimed at carrying out helioseismic
studies of the subsurface structure of the Sun and its dynamics. The participation of the Ulugh Beg Astronomical Institute in both
projects was crucial not only for obtaining long-term observational
data, but also for the scientific analyses of the observational data
and the preparation of the resulting research papers. Many scientific
results came out of these two projects, but more importantly, many
graduate students used these projects to obtain their Ph.D.s.

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Title: Early South Pole Observations and the IRIS Network: The
Quarter Century History of a Small Sodium Cell
Authors: Fossat, E.
2013ASPC..478...73F Altcode:
This is a brief list of snapshots along my personal scientific
trajectory, which has interestingly met 30 years of the initial
development of helioseismology.

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Title: New insights into the dust formation of oxygen-rich AGB stars
Authors: Karovicova, I.; Wittkowski, M.; Ohnaka, K.; Boboltz, D. A.;
Fossat, E.; Scholz, M.
2013A&A...560A..75K Altcode: 2013arXiv1310.1924K
Context. Asymptotic giant branch (AGB) stars are one of the major
sources of dust in the universe. The formation of molecules and dust
grains and their subsequent expulsion into the interstellar medium
via strong stellar winds is under intense investigation. This is in
particular true for oxygen-rich stars, for which the path of dust
formation has remained unclear. Aims: We conducted spatially
and spectrally resolved mid-infrared multi-epoch interferometric
observations to investigate the dust formation process in the extended
atmospheres of oxygen-rich AGB stars. Methods: We observed the
Mira variable AGB stars S Ori, GX Mon, and R Cnc between February 2006
and March 2009 with the MIDI instrument at the VLT interferometer. We
compared the data to radiative transfer models of the dust shells, where
the central stellar intensity profiles were described by dust-free
dynamic model atmospheres. We used Al2O3 and
warm silicate grains, following earlier studies in the literature. Results: Our S Ori and R Cnc data could be well described by an
Al2O3 dust shell alone, and our GX Mon data by
a mix of an Al2O3 and a silicate shell. The
best-fit parameters for S Ori and R Cnc included photospheric
angular diameters ΘPhot of 9.7 ± 1.0 mas and 12.3 ±
1.0 mas, optical depths τV(Al2O3)
of 1.5 ± 0.5 and 1.35 ± 0.2, and inner radii Rin
of 1.9 ± 0.3 RPhot and 2.2 ± 0.3 RPhot,
respectively. Best-fit parameters for GX Mon were ΘPhot
= 8.7 ± 1.3 mas, τV(Al2O3) =
1.9 ± 0.6, Rin(Al2O3) = 2.1 ±
0.3 RPhot, τV(silicate)= 3.2 ± 0.5, and
Rin(silicate)= 4.6 ± 0.2 RPhot. Our data did
not show evidence of intra-cycle and cycle-to-cycle variability or of
asymmetries within the error-bars and within the limits of our baseline
and phase coverage. Conclusions: Our model fits constrain the
chemical composition and the inner boundary radii of the dust shells,
as well as the photospheric angular diameters. Our interferometric
results are consistent with Al2O3 grains
condensing close to the stellar surface at about 2 stellar radii,
co-located with the extended atmosphere and SiO maser emission,
and warm silicate grains at larger distances of about 4-5 stellar
radii. We verified that the number densities of aluminum can match
that of the best-fit Al2O3 dust shell near the
inner dust radius in sufficiently extended atmospheres, confirming that
Al2O3 grains can be seed particles for the further
dust condensation. Together with literature data of the mass-loss rates,
our sample is consistent with a hypothesis that stars with low mass-loss
rates form primarily dust that preserves the spectral properties of
Al2O3, and stars with higher mass-loss rate form
dust with properties of warm silicates. Based on observations made
with the Very Large Telescope Interferometer (VLTI) at the Paranal
Observatory under program IDs 073.D-0711, 075.D-0097, 077.D-0630,
079.D-0172, and 082.D-0723.Tables 1-3, 8, 9 are available in electronic
form at <A href="http://www.aanda.org">http://www.aanda.org</A>

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Title: Mid-infrared interferometric observations of four oxygen-rich
Mira variables
Authors: Karovicova, I.; Wittkowski, M.; Ohnaka, K.; Boboltz, D. A.;
Fossat, E.; Scholz, M.
2013EAS....63..191K Altcode:
We present an investigation of the dust formation process in the
atmospheres of the oxygen-rich AGB stars RR Aql, S Ori, GX Mon and R Cnc
using spatially and spectrally resolved mid-infrared interferometric
observations. We successfully compared multi epoch observations to a
radiative transfer model of the dust shells, where the central stellar
intensity profile is described by a series of dust-free dynamic
model atmospheres based on self-excited pulsation models. We show
that the Al2O3 shells have inner radii between
1.9 and 2.2 stellar photospheric radii, and that the silicate shells
have inner radii between 4.1 and 4.6 stellar photospheric radii. The
best-fit photospheric angular diameters are consistent with independent
estimates. The model dust temperatures at the inner radii of 1.9-2.2
stellar radii and 4.1-4.6 stellar radii are consistent with dust
condensation temperatures of Al2O3 and silicates,
respectively.

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Title: Dome C site testing: long term statistics of integrated
optical turbulence parameters at ground level
Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Ziad, A.; Abe, L.;
Bondoux, E.; Bouchez, G.; Challita, Z.; Jeanneaux, F.; Mékarnia,
D.; Petermann, D.; Pouzenc, C.
2013IAUS..288..300A Altcode:
We present long term site testing statistics based on DIMM and GSM
data obtained at Dome C, Antarctica. These data have been collected
on the bright star Canopus since the end of 2003. We give values
of the integrated turbulence parameters in the visible (wavelength
500 nm). The median value we obtained for the seeing are 1.2 arcsec,
2.0 arcsec and 0.8 arcsec at respective elevations of 8m, 3m and 20m
above the ground. The isoplanatic angle median value is 4.0 arcsec
and the median outer scale is 7.5m. We found that both the seeing
and the isoplanatic angle exhibit a strong dependence with the season
(the seeing is larger in winter while the isoplanatic angle is smaller).

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Title: Site testing for submillimetre astronomy at Dome C, Antarctica
Authors: Tremblin, P.; Minier, V.; Schneider, N.; Durand, G. Al.;
Ashley, M. C. B.; Lawrence, J. S.; Luong-van, D. M.; Storey, J. W. V.;
Durand, G. An.; Reinert, Y.; Veyssiere, C.; Walter, C.; Ade, P.;
Calisse, P. G.; Challita, Z.; Fossat, E.; Sabbatini, L.; Pellegrini,
A.; Ricaud, P.; Urban, J.
2011A&A...535A.112T Altcode: 2011arXiv1110.4311T
 Aims: Over the past few years a major effort has been put into
the exploration of potential sites for the deployment of submillimetre
astronomical facilities. Amongst the most important sites are Dome C and
Dome A on the Antarctic Plateau, and the Chajnantor area in Chile. In
this context, we report on measurements of the sky opacity at 200 μm
over a period of three years at the French-Italian station, Concordia,
at Dome C, Antarctica. We also present some solutions to the challenges
of operating in the harsh polar environment. Methods: The 200-μm
atmospheric opacity was measured with a tipper. The forward atmospheric
model MOLIERE (Microwave Observation LIne Estimation and REtrieval)
was used to calculate the atmospheric transmission and to evaluate
the precipitable water vapour content (PWV) from the observed sky
opacity. These results have been compared with satellite measurements
from the Infrared Atmospheric Sounding Interferometer (IASI) on Metop-A,
with balloon humidity sondes and with results obtained by a ground-based
microwave radiometer (HAMSTRAD). In addition, a series of experiments
has been designed to study frost formation on surfaces, and the temporal
and spatial evolution of thermal gradients in the low atmosphere. Results: Dome C offers exceptional conditions in terms of absolute
atmospheric transmission and stability for submillimetre astronomy. Over
the austral winter the PWV exhibits long periods during which it is
stable and at a very low level (0.1 to 0.3 mm). Higher values (0.2 to
0.8 mm) of PWV are observed during the short summer period. Based on
observations over three years, a transmission of around 50% at 350
μm is achieved for 75% of the time. The 200-μm window opens with
a typical transmission of 10% to 15% for 25% of the time. 
Conclusions: Dome C is one of the best accessible sites on Earth for
submillimetre astronomy. Observations at 350 or 450 μm are possible
all year round, and the 200-μm window opens long enough and with a
sufficient transparency to be useful. Although the polar environment
severely constrains hardware design, a permanent observatory with
appropriate technical capabilities is feasible. Because of the very
good astronomical conditions, high angular resolution and time series
(multi-year) observations at Dome C with a medium size single dish
telescope would enable unique studies to be conducted, some of which
are not otherwise feasible even from space.

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Title: Multi-Epoch Mid-Infrared Interferometric Observations of the
Oxygen-rich Mira Variable Star RR Aql with the VLTI/MIDI Instrument
Authors: Karovicova, I.; Wittkowski, M.; Boboltz, D. A.; Fossat, E.;
Ohnaka, K.; Scholz, M.
2011ASPC..445..269K Altcode:
This work is part of an on-going program of multi-epoch simultaneous
observations of a sample of four evolved stars — RR Aql, GX Mon,
S Ori, and AH Sco — using the VLTI and VLBA facilities. Different
pulsating layers and their relative positions are monitored across
phases and cycles. Here, we present mid-infrared interferometric
observations of the oxygen-rich Mira variable RR Aql at 13 epochs
covering 4 pulsation cycles with the MIDI instrument at the VLTI. We
modeled the observed data using dust-free self-excited dynamic model
atmospheres combined with an ad-hoc radiative transfer model of
the dust shell. This study represents the first comparison between
interferometric observations and dynamic models over an extended
range of pulsation phases covering several cycles. We show that
the combination of the models describe the observed data well. We
determine the best dust-free dynamical model atmosphere and the best
dust shell parameters including the optical depth of the two examined
dust species (Al2O3 and silicates), the inner
boundary radii of the dust shells, the density distribution, and the
continuum photospheric angular diameter for all epochs. The results
indicate that silicate is the major chemical component in the dust
shell. We also compare the data with equivalent uniform disk (UD)
and Gaussian FWHM diameters.

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Title: Molecular and Dusty Layers of Asymptotic Giant Branch Stars
Studied with the VLT Interferometer
Authors: Wittkowski, M.; Karovicova, I.; Boboltz, D. A.; Fossat,
E.; Ireland, M.; Ohnaka, K.; Scholz, M.; van Wyk, F.; Whitelock, P.;
Wood, P. R.; Zijlstra, A. A.
2011Msngr.145...24W Altcode:
Mass loss from asymptotic giant branch (AGB) stars is the most important
driver for the evolution of low to intermediate mass stars towards
planetary nebulae. It is also one of the most important sources
of chemical enrichment of the interstellar medium. The mass-loss
process originates in the extended atmosphere, whose structure is
affected by stellar pulsations, and where molecular and dusty layers
are formed. Optical interferometry resolves the extended atmospheres
of AGB stars and thereby enables us to obtain measurements of the
intensity profile across this region. We present an overview of recent
results from our spectro-interferometric observations of AGB stars
using the near- and mid-infrared instruments AMBER and MIDI of the
VLT Interferometer.

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Title: Mid-infrared interferometric monitoring of evolved stars. The
dust shell around the Mira variable RR Aquilae at 13 epochs
Authors: Karovicova, I.; Wittkowski, M.; Boboltz, D. A.; Fossat, E.;
Ohnaka, K.; Scholz, M.
2011A&A...532A.134K Altcode: 2011arXiv1107.0909K
 Aims: We present a unique multi-epoch infrared interferometric
study of the oxygen-rich Mira variable RR Aql in comparison to radiative
transfer models of the dust shell. We investigate flux and visibility
spectra at 8-13 μm with the aim of better understanding the pulsation
mechanism and its connection to the dust condensation sequence and
mass-loss process. Methods: We obtained 13 epochs of mid-infrared
interferometry with the MIDI instrument at the VLTI between April
2004 and July 2007, covering minimum to pre-maximum pulsation phases
(0.45-0.85) within four cycles. The data are modeled with a radiative
transfer model of the dust shell where the central stellar intensity
profile is described by a series of dust-free dynamic model atmospheres
based on self-excited pulsation models. We examined two dust species,
silicate and Al2O3 grains. We performed model
simulations using variations in model phase and dust shell parameters to
investigate the expected variability of our mid-infrared photometric and
interferometric data. Results: The observed visibility spectra do
not show any indication of variations as a function of pulsation phase
and cycle. The observed photometry spectra may indicate intracycle and
cycle-to-cycle variations at the level of 1-2 standard deviations. The
photometric and visibility spectra of RR Aql can be described well by
the radiative transfer model of the dust shell that uses a dynamic
model atmosphere describing the central source. The best-fitting
model for our average pulsation phase of overline{Φ_V=0.64±0.15}
includes the dynamic model atmosphere M21n (Tmodel =
2550 K) with a photospheric angular diameter of θPhot
= 7.6 ± 0.6 mas, and a silicate dust shell with an optical depth of
τV = 2.8 ± 0.8, an inner radius of Rin = 4.1 ±
0.7 RPhot, and a power-law index of the density distribution
of p = 2.6 ± 0.3. The addition of an Al2O3 dust
shell did not improve the model fit. However, our model simulations
indicate that the presence of an inner Al2O3
dust shell with lower optical depth than for the silicate dust shell
can not be excluded. The photospheric angular diameter corresponds
to a radius of R_phot=520+230-140 R_⊙ and an
effective temperature of Teff 2420 ± 200 K. Our modeling
simulations confirm that significant intracycle and cycle-to-cycle
visibility variations are not expected for RR Aql at mid-infrared
wavelengths within our uncertainties. Conclusions: We conclude that our
RR Aql data can be described by a pulsating atmosphere surrounded by a
silicate dust shell. The effects of the pulsation on the mid-infrared
flux and visibility values are expected to be less than about 25%
and 20%, respectively, and are too low to be detected within our
measurement uncertainties. Based on observations made with Very
Large Telescope Interferometer (VLTI) at the Paranal Observatory under
program IDs 073.D-0711, 075.D-0097, 077.D-0630, and 079.D-0172.Figure
5 is available in electronic form at http://www.aanda.org

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Title: Some results after 10 years of site testing at Concordia,
Antarctica
Authors: Fossat, Eric
2011arXiv1101.3210F Altcode:
At an altitude of 3250m and at a latitude of $75^\circ$S, the
Italo-French Concordia station was open to winter-over teams in
2005. It is one of the high points of the Antarctic polar plateau. These
extreme remote sites are expected to provide exceptional conditions for
astronomical observations, specially in the infra-red ranges, given
the very cold winter temperatures, averaging well below -60C. Being
very flat as highest points of that very broad polar plateau, they are
also not subject to the famous katabatic winds that can be devastating
on the Antarctic coast, and in fact their mean wind speed along the
year are the weakest known on Earth, less than 3 m/s. Besides the
resulting absence of danger that such winds would present for large
size optical instruments, this situation offers another benefit, which
is an excellent free atmosphere seeing above a very thin but turbulent
surface layer. This paper emphasizes these seeing peculiarities, but
not only. It is presented as simply following a significant fraction
of my slide presentation during the meeting.

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Title: Typical duration of good seeing sequences at Concordia
Authors: Fossat, E.; Aristidi, E.; Agabi, A.; Bondoux, E.; Challita,
Z.; Jeanneaux, F.; Mékarnia, D.
2010A&A...517A..69F Altcode: 2010arXiv1003.3583F
Context. The winter seeing at Concordia is bimodal, i.e. either
excellent or quite poor, depending on the altitude above the
snow surface. We study the temporal behavior of the good seeing
sequences. Efficient exploitation of extremely good seeing conditions
with an adaptive optics system requires long integrations. 
Aims: We examine the temporal distribution of time intervals providing
excellent seeing at Concordia. Methods: We create temporal
windows of good seeing by applying a simple binary process: good or
bad. We correct the autocorrelations of these windows for those of
the existing data sets, since these are not continuous, often being
interrupted by technical problems in addition to the adverse weather
gaps. We infer the typical duration of good seeing sequences from these
corrected autocorrelations. This study has to be a little detailed as
its results depend on the season, summer or winter. Results:
When we adopt a threshold of 0.5 arcsec to define “good seeing”, we
find that three characteristic numbers describe the temporal evolution
of the good seeing windows. The first number is the mean duration of
an uninterrupted good seeing sequence, which is τ0 = 7.5 h
at 8 m above the ground and 15 h at 20 m. These sequences are randomly
distributed in time, following a negative exponential law of damping
time τ1 = 29 h (at elevation 8 m and 20 m), which represents
our second number. The third number is the mean time between two 29 h
episodes, which is T = 10 days at 8 m high (5 days at 20 m). 
Conclusions: There is certainly no other site on Earth, except for
the few other high altitude Domes on the Antarctic plateau, at which
we can achieve these exceptionally high quality seeing conditions.

---------------------------------------------------------
Title: Studying the vertical extent of the ground layer turbulence
using sonic-anemometers
Authors: Travouillon, T.; Aristidi, E.; Fossat, E.; Bondoux, E.;
Challita, Z.; Mekarnia, D.; Jeanneaux, F.; Odoardi, D.; Lawrence, J. S.
2010EAS....40..115T Altcode:
The optical turbulence above Dome C in winter is mainly concentrated
in the first tens of meters above the ground. The properties of this
so-called surface layer were investigated during the last two winterover
by a set of sonics anemometers placed on a 45 m high tower. These
anemometers provide measurements of the temperature and the wind speed
vector. The sampling rate of 10 Hz allows to derivate the refractive
index structure constant C_n^2. We report here the first analysis of
these data.

---------------------------------------------------------
Title: Dome C boundary layer and seeing peculiarities
Authors: Fossat, E.; Aristidi, E.; Astroconcordia Team
2010EAS....40...73F Altcode:
This paper presents some statistical information about the Concordia
turbulent surface inversion layer, regarding height and turbulent
energy, its contribution to the peculiar local seeing, and the free
atmosphere seeing encountered just above this surface layer.

---------------------------------------------------------
Title: Implications of Turbulence Optical Parameters on HAR Techniques
at Dome C
Authors: Ziad, A.; Aristidi, E.; Agabi, A.; Fossat, E.; Borgnino,
J.; Maire, J.; Martin, F.
2010EAS....40...21Z Altcode:
The HAR observing methods such as Adaptive Optics and Interferometery,
require a better understanding of the behavior of the perturbed
wavefronts, more exactly a better knowledge of the atmospheric
turbulence model in addition to the associate parameters. This is
very crucial for modeling the HAR techniques and particularly for the
evaluation of their performance. Indeed, it is well-known that the
performance of an AO system depends upon the seeing conditions, the
outer scale, the isoplanatic angle and the coherence time. A review
of the site-testing instruments deployed at Dome C will be given,
their pertinence and their implications on HAR techniques will be
discussed comparatively to the Paranal site.

---------------------------------------------------------
Title: Dome C site testing: surface layer, free atmosphere seeing,
and isoplanatic angle statistics
Authors: Aristidi, E.; Fossat, E.; Agabi, A.; Mékarnia, D.; Jeanneaux,
F.; Bondoux, E.; Challita, Z.; Ziad, A.; Vernin, J.; Trinquet, H.
2009A&A...499..955A Altcode: 2009arXiv0904.2982A
This paper analyses 3 1/2 years of site testing data obtained at
Dome C, Antarctica, based on measurements obtained with three DIMMs
located at three different elevations. Basic statistics of the seeing
and the isoplanatic angle are given, as well as the characteristic
time of temporal fluctuations of these two parameters, which we found
to around 30 min at 8 m. The 3 DIMMs are exploited as a profiler of
the surface layer, and provide a robust estimation of its statistical
properties. It appears to have a very sharp upper limit (less than 1
m). The fraction of time spent by each telescope above the top of the
surface layer permits us to deduce a median height of between 23 m and
27 m. The comparison of the different data sets led us to infer the
statistical properties of the free atmosphere seeing, with a median
value of 0.36 arcsec. The C_n2 profile inside the surface
layer is also deduced from the seeing data obtained during the fraction
of time spent by the 3 telescopes inside this turbulence. Statistically,
the surface layer, except during the 3-month summer season, contributes
to 95 percent of the total turbulence from the surface level, thus
confirming the exceptional quality of the site above it.

---------------------------------------------------------
Title: First statistics of the turbulence outer scale at Dome C
Authors: Ziad, A.; Aristidi, E.; Agabi, A.; Borgnino, J.; Martin,
F.; Fossat, E.
2008A&A...491..917Z Altcode:
Context: The outer scale of wavefronts is of interest for the
dimensioning and the optimisation of the High Angular Resolution
techniques such as Interferometry and Adaptive Optics, particularly for
the new generation of telescopes such as the Extremely Large Telescopes
(ELT). Aims: We aim to provide the first statistics of the outer
scale at Dome C site in Antarctica to finalize the characterization of
this site. Methods: A new version of the Generalized Seeing
Monitor has been developed for extremely cold conditions. Two
DIMMs (Differential Image Motion Monitor) were coupled to extract
Angle-of-Arrival (AA) fluctuations using CCD detectors. Correlations
of these AA fluctuations for different baselines lead to outer scale
estimations. Results: For the first time, statistics of the outer
scale at Dome C are provided leading to small values in the surface
layer at Dome C. These small outer scale values compared to temperate
sites considerably reduce the fringe excursion of interferometers
and the low orders of the normalized amplitude of atmospheric Zernike
coefficients, particularly the tip-tilt. Conclusions: The Dome
C small outer scale combined with the large coherence time and large
isoplanatic angle are very useful for the development of Adaptive
Optics systems and long-baseline interferometers.

---------------------------------------------------------
Title: SYMPA, a dedicated instrument for Jovian seismology. II. Real
performance and first results
Authors: Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Alvarez, M.;
Reyes-Ruiz, M.; Belmonte, J. A.; Fossat, E.; Jeanneaux, F.; Valtier,
J. -C.
2008A&A...490..859G Altcode: 2008arXiv0802.1777G
Aims: SYMPA is the first instrument dedicated to the observation of free
oscillations of Jupiter. Its principles and theoretical performance
have been presented in Paper I. This second paper describes the data
processing method, the real instrumental performance and presents
the first results of a Jovian observation run, lead in 2005 at
Teide Observatory. Methods: SYMPA is a Fourier transform
spectrometer which works at a fixed optical path difference. It
produces Doppler shift maps of the observed object. The velocity
amplitude of Jupiter's oscillations is expected to be below 60 cm
s-1. Results: Despite light technical defects, the
instrument was demonstrated to work correctly, being limited only by
photon noise. A noise level of about 12 cm s-1 was reached
on a 10-night observation run, with 21% duty cycle, which is 5 time
better than similar previous observations. However, no signal from
Jupiter is clearly highlighted.

---------------------------------------------------------
Title: Optical turbulence and outer scales above Dome C in Antarctica
Authors: Trinquet, Hervé; Agabi, Abdelkrim; Vernin, Jean; Azouit,
Max; Aristidi, Eric; Fossat, Eric
2008SPIE.7012E..25T Altcode: 2008SPIE.7012E..75T
Dome C in Antarctica is a particular astronomical site when considering
the optical turbulence conditions. From the first winterover
campaign performed in 2005 at Dome C, the set of 34 meteorological
balloon profiles has been analyzed. The meteorological balloons were
equipped with microthermal sensors used to sense the vertical profile
of the optical turbulence intensity C2n. The
C2n median profile, mean temperature and mean
horizontal wind speed are given. The C2n median
profile is characterized by a very strong and thin turbulent surface
layer. The surface layer height is defined. The median outer scale
profile at Dome C is computed using the Tatarski definition. The von
Karman outer scale is also deduced. The integrated parameters as Fried
parameter r0, coherence time τ0, isoplanatic
angle θ0 and the spatial-coherence outer scale L0
used to define astronomical site quality, are computed at 8 m above
the ground and above the turbulent surface layer.

---------------------------------------------------------
Title: IRAN: laboratory test bench for hypertelescope pupil-plane
recombination
Authors: Allouche, F.; Vakili, F.; Glindemann, A.; Aristidi, E.; Abe,
L.; Fossat, E.; Douet, R.
2008SPIE.7013E..3TA Altcode: 2008SPIE.7013E.117A
In 2004, our group proposed IRAN, an alternative beam-combination
technique to the so-called hypertelescope imaging method introduced by
Labeyrie in the 1990s. We have recently set up a laboratory experiment
aiming at validating our image densification approach instead of the
pupil densification scheme of Labeyrie. In our experiment, seven
sub-apertures illuminated by laser sources are recombined using
the IRAN scheme. The validation of the IRAN recombination consists
basically in retrieving the point-spread intensity distribution
(PSID), demonstrating the conservation of the object-image convolution
relation. We will introduce IRAN, compare it to the hyper-telescope,
and present the experimental results that we obtained.

---------------------------------------------------------
Title: Sampling the ground layer of the atmosphere at Dome C using
fast sonic-anemometers
Authors: Travouillon, T.; Aristidi, E.; Fossat, E.; Lawrence, J. S.;
Mekarnia, D.; Moore, A. M.; Skidmore, A. W.; Storey, J. W. V.
2008SPIE.7012E..4BT Altcode: 2008SPIE.7012E.147T
The ground layer turbulence at Dome C is the cause for more than
90% of the total turbulence column. While the height of this layer
has been currently measured to be approximately 30m, no long term
statistics is available from this part of the atmosphere. In order to
plan the construction of future telescope at this site temperature
site, temperature, wind speed and turbulence measurements are also
necessary. Using fast sonicanemometers we present, a preliminary set
of data covering January to October 2007 sampling these quantities at
heights of 8, 16 and 28 meters.

---------------------------------------------------------
Title: Nighttime Optical Turbulence Vertical Structure above Dome
C in Antarctica
Authors: Trinquet, Hervé; Agabi, Abdelkrim; Vernin, Jean; Azouit,
Max; Aristidi, Eric; Fossat, Eric
2008PASP..120..203T Altcode:
During the austral winter 2005, the first astronomical site testing
campaign were performed at Dome C, in Antarctica. Thirty-five
meteorological balloons equipped with microthermal sensors were used
to sense the vertical profile of the optical turbulence intensity
above Dome C up to 20 km. All the profiles of the 2005 campaign are
statistically analyzed. We provide the median profiles and the mean
potential temperature, mean horizontal wind speed, and mean direction
profiles for the three seasons covered by this campaign (autumn,
winter, and beginning of the spring). The structure of the optical
turbulence in the atmosphere above Dome C is analyzed and compared
with the well-known median profiles of midlatitude sites. Of the whole
optical turbulence, 80% lies within the first 33 m above the ground
and 9% in the upper part of the boundary layer, between 33 m and 1 km
above the ground. The remaining 11% are in the free atmosphere. This
is an extreme situation when compared with “classical” midlatitude
sites where the surface layer extends up to 200 m. This strong and
thin surface layer is the result of the kinetic turbulent mixing
of air combined with a strong potential temperature gradient. The
site is characterized from the adaptive optics point of view. Seeing,
isoplanatic angle, and coherence time are estimated for each considered
seasons. A four-layer decomposition for each season is provided for
adaptive optics simulations. For high angular astronomy, a telescope at
Dome C needs to be elevated over this surface layer, or a specific GLAO
needs to be designed. Combined with the unique possibility of performing
continuous observation from Antarctica, scientific programs such as
microlensing, pulsating stars, and asteroseismology become feasible.

---------------------------------------------------------
Title: Dome C site testing results
Authors: Fossat, E.
2008EAS....33....5F Altcode:
The first site testing campaigns started at Dome C during the summer
season 2000 2001. Since then, each further summer has been exploited,
as well as the first three winter seasons permitted by the opening of
the Concordia station in 2005. Many of the astronomical site properties
begin now to be well known, although some more still need to be adressed
and more statistics is obviously required.

---------------------------------------------------------
Title: Inter-Division Ix-X / Working Group Encouraging the
International Development of Antarctic Astronomy
Authors: Burton, Michael G.; Busso, Maurizio; Fossat, Eric G.; Lloyd,
James P.; McCaughrean, Mark J.; Spiering, Christian; Tori, Shoji
2007IAUTB..26..188B Altcode:
The business session of the Working Group followed the completion
of Special Session 7, Astronomy in Antarctica. The proceedings of
this meeting are published in Highlights in Astronomy, Volume 14
(Ed. K. A. van der Hucht, 2007, CUP). The session involved 18 papers
spread over 5 sessions, together with a further 18 poster papers. A
dinner was also held in Prague following the first day of the Special
Session.

---------------------------------------------------------
Title: SYMPA, a dedicated instrument for Jovian
seismology. I. Principle and performance
Authors: Schmider, F. X.; Gay, J.; Gaulme, P.; Jacob, C.; Abe, L.;
Alvarez, M.; Belmonte, J. A.; Fossat, E.; Gelly, B.; Guillot, T.;
Jeanneaux, F.; Mosser, B.; Valtier, J. -C.
2007A&A...474.1073S Altcode:
Aims:The detection and measurement of acoustic modes on the giant
planets of the solar system is of great interest for the study of the
internal structure and evolution of the giant planets, as well as
the study of the solar system formation. Such observations require
a dedicated instrument and observing procedure. Methods: We
describe the principle and the performance of an instrument dedicated
to seismology of giant planets. In this first paper, we describe
the principle and the optical scheme, and derive the theoretical
performances. As for the Sun, it is possible to measure modes with
spatial resolution, but a larger collecting area is necessary. As for
asteroseismology in general, continuity in the observation is also
required. Results: From results obtained at the laboratory,
we derive the actual performance of the instrument and estimate its
capabilities in network observations. Conclusions: We demonstrate
that the proposed instrument and strategy is adapted for the seismology
of giant planets. In a second paper, we will present the first data
set obtained with it, explain the data reduction procedure, and present
preliminary results.

---------------------------------------------------------
Title: Site testing at Dome C: history and present status
Authors: Vernin, Jean; Agabi, Abdelkrim; Aristidi, Eric; Azouit, Max;
Chadid, Merieme; Fossat, Eric; Sadibekova, Tatiana; Trinquet, Hervé;
Ziad, Aziz
2007HiA....14..693V Altcode:
The idea of starting an astronomical site testing in Antarctica
began during a congress organized by French Académie des Sciences,
in 1992, and entitled ‘Recherches polaires-Une Stratégie pour
l'an 2000’. At this time, one of us (Vernin 1994) gave a proposal
for an astronomical site testing in Antarctica. This proposal was
rapidly followed by a meeting between Al Harper (from ‘Center for
Astrophysical Research in Antarctica’, Chicago), Peter Gillingham
(from the Anglo Australian Observatory, Australia) and Jean Vernin
(from Nice University) at Lake Geneva, Wisconsin, in 1993. It was
decided to investigate what was the astronomical quality of South
Pole station, each institute bringing its own participation: CARA,
the South Pole infrastructure, University of New South Wales, a PhD
student and Nice University its expertise and instruments.

---------------------------------------------------------
Title: Multi-aperture interferometry at Concordia
Authors: Fossat, Eric; Vakili, Farrokh; Aristidi, Eric; Lopez,
Bruno; Schmider, François-Xavier; Agabi, Karim; Daban, Jean-Baptiste;
Allouche, Fatmé; Belu, Adrian; Gori, Pierre-Marie; Guerri, Géraldine;
Valat, Bruno
2007HiA....14..705F Altcode:
The next generation (post-VLTI) of multi-telescope interferometric
arrays operated in optical/infrared wavelengths should be kilometric,
from 1 to 10 km. The Concordia station offers a unique opportunity to
set such an interferometer in the best atmospheric conditions presently
known on Earth.

---------------------------------------------------------
Title: Atmospheric scintillation at Dome C, Antarctica
Authors: Kenyon, Suzanne L.; Lawrence, Jon S.; Ashley, Michael C. B.;
Storey, John W. V.; Tokovinin, Andrei; Fossat, Eric
2007HiA....14..698K Altcode:
Dome C, Antarctica is one of the most promising astronomical sites in
the world (Fossat &amp; Candidi 2003, and references therein). Dome
C boasts low wind speeds, very cold temperatures and little
precipitation. The atmospheric turbulence is very weak compared to
temperate sites, leading to sub-arcsecond seeing conditions (Lawrence
et al. 2004; Agabi et al. 2006).

---------------------------------------------------------
Title: Asteroseismology at Dome C in Antarctica
Authors: Fossat, Eric
2007CoAst.150..307F Altcode:
The Antarctica plateau, at altitudes between 3 and 4 kilometres, offers
the best possible sky for many astronomical purposes. Among these are
the need for an excellent sky transparency, a heavily reduced level of
scintillation and the possibility of very long times of integration
only interrupted by rare clouds. So, asteroseismology observations
using both photometry and spectroscopy are among the first scientific
targets for the next few years at the Italo-French Concordia station,
that is now open for winter-over activity since February, 2005. I
briefly described the site testing activity and what we already know
of the sky quality, and then the asteroseismic programmes that are
likely to start within the next 5 years or so.

---------------------------------------------------------
Title: Jovian seismology: preliminary results of the SYMPA instrument
Authors: Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Jeanneaux,
F.; Fossat, E.; Valtier, J. C.; Alvarez, M.; Reyes, M.
2007CoAst.150..313G Altcode:
Jupiter's internal structure is poorly known (Guillot et
al. 1997). Seismology is a powerful tool to investigate the internal
structure of planets and stars, by analysing how acoustic waves
propagate. Mosser (1997) and Gudkova &amp; Zarkhov (1999) showed
that the detection and the identification of non-radial modes up to
degree ℓ=25 can constrain strongly the internal structure. SYMPA is
a ground-based network project dedicated to the Jovian oscillations
(Schmider et al. 2002). The instrument is composed of a Mach-Zehnder
interferometer which produces four interferograms of the planetary
spectrum. The combination of the four images in phase quadrature allows
the reconstruction of the incident light phase, which is related to
the Doppler shift generated by the oscillations. Two SYMPA instruments
were built at the Nice university and were used simultaneously during
two observation campaigns, in 2004 and 2005, at the San Pedro Martir
Observatory (Mexico) and the Izana Observatory (Las Canarias). We
present for the first time the data processing and the preliminary
results of the experiment.

---------------------------------------------------------
Title: Astronomy at Dome C: an overview
Authors: Fossat, Eric
2007sfaa.confE...6F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: AMBER, the near-infrared spectro-interferometric
three-telescope VLTI instrument
Authors: Petrov, R. G.; Malbet, F.; Weigelt, G.; Antonelli, P.;
Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.;
Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi,
F.; Millour, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois,
S.; Roussel, A.; Salinari, P.; Tatulli, E.; Zins, G.; Accardo, M.;
Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa,
C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing,
F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano
de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille,
T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.;
Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera,
O.; Hofmann, K. -H.; Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel,
D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard,
Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège,
P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka,
K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.;
Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller,
M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tallon, M.;
Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe,
O.; Valtier, J. -C.; Vannier, M.; Ventura, N.
2007A&A...464....1P Altcode:
Context: Optical long-baseline interferometry is moving a crucial
step forward with the advent of general-user scientific instruments
that equip large aperture and hectometric baseline facilities,
such as the Very Large Telescope Interferometer (VLTI). Aims:
AMBER is one of the VLTI instruments that combines up to three beams
with low, moderate and high spectral resolutions in order to provide
milli-arcsecond spatial resolution for compact astrophysical sources
in the near-infrared wavelength domain. Its main specifications are
based on three key programs on young stellar objects, active galactic
nuclei central regions, masses, and spectra of hot extra-solar
planets. Methods: These key science goals led to scientific
specifications, which were used to propose and then validate the
instrument concept. AMBER uses single-mode fibers to filter the entrance
signal and to reach highly accurate, multiaxial three-beam combination,
yielding three baselines and a closure phase, three spectral dispersive
elements, and specific self-calibration procedures. Results: The
AMBER measurements yield spectrally dispersed calibrated visibilities,
color-differential complex visibilities, and a closure phase allows
astronomers to contemplate rudimentary imaging and highly accurate
visibility and phase differential measurements. AMBER was installed
in 2004 at the Paranal Observatory. We describe here the present
implementation of the instrument in the configuration with which the
astronomical community can access it. Conclusions: .After two
years of commissioning tests and preliminary observations, AMBER has
produced its first refereed publications, allowing assessment of its
scientific potential.

---------------------------------------------------------
Title: An asymmetry detected in the disk of <ASTROBJ>κ Canis
Majoris</ASTROBJ> with AMBER/VLTI
Authors: Meilland, A.; Millour, F.; Stee, P.; Domiciano de Souza, A.;
Petrov, R. G.; Mourard, D.; Jankov, S.; Robbe-Dubois, S.; Spang, A.;
Aristidi, E.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Chelli, A.;
Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Lagarde,
S.; Le Coarer, E.; Lisi, F.; Malbet, F.; Perraut, K.; Puget, P.;
Rantakyrö, F.; Roussel, A.; Tatulli, E.; Weigelt, G.; Zins, G.;
Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Baffa,
C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing,
F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Driebe,
T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy,
R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin,
A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.;
Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.;
Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.;
Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet,
D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.;
Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.;
Schertl, D.; Schöller, M.; Solscheid, W.; Stefanini, P.; Tallon,
M.; Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe,
O.; Valtier, J. -C.; Vannier, M.; Ventura, N.
2007A&A...464...73M Altcode: 2006astro.ph.11563M
Aims:We study the geometry and kinematics of the circumstellar
environment of the Be star κ CMa in the Brγ emission line and its
nearby continuum. Methods: We use the AMBER/VLTI instrument
operating in the K band, which provides a spatial resolution of about 6
mas with a spectral resolution of 1500, to study the kinematics within
the disk and to infer its rotation law. To obtain more kinematical
constraints we also use a high spectral resolution Paβ line profile
obtain in December 2005 at the Observatorio do Pico do Dios, Brazil and
we compile V/R line profile variations and spectral energy distribution
data points from the literature. Results: Using differential
visibilities and differential phases across the Brγ line we detect an
asymmetry in the disk. Moreover, we found that κ CMa seems difficult to
fit within the classical scenario for Be stars, illustrated recently
by α Arae observations, i.e. a fast rotating B star close to its
breakup velocity surrounded by a Keplerian circumstellar disk with
an enhanced polar wind. We discuss the possibility that κ CMa is a
critical rotator with a Keplerian rotating disk and examine whether if
the detected asymmetry can be interpreted within the “one-armed”
viscous disk framework. Based on observations collected at the
European Southern Observatory, Paranal, Chile, within the guaranteed
time programme 074.A-9025(A).

---------------------------------------------------------
Title: Constraining the wind launching region in Herbig Ae stars:
AMBER/VLTI spectroscopy of HD 104237
Authors: Tatulli, E.; Isella, A.; Natta, A.; Testi, L.; Marconi, A.;
Malbet, F.; Stee, P.; Petrov, R. G.; Millour, F.; Chelli, A.; Duvert,
G.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Dugué, M.; Gennari, S.;
Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut,
K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Weigelt,
G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki,
B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme,
S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot,
C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier,
P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet,
D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.;
Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.; Kamm, D.;
Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.; Lesourd,
T.; Lopez, B.; Lopez, M.; Magnard, Y.; Mars, G.; Martinot-Lagarde,
G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Mourard,
D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.;
Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.;
Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stefanini, P.;
Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Vakili, F.; von der Lühe,
O.; Valtier, J. -C.; Vannier, M.; Ventura, N.
2007A&A...464...55T Altcode: 2006astro.ph..6684T
Aims:We investigate the origin of the Brγ emission of the Herbig
Ae star HD 104237 on Astronomical Unit (AU) scales. Methods:
Using AMBER/VLTI at a spectral resolution R=1500 we spatially resolve
the emission in both the Brγ line and the adjacent continuum. Results: The visibility does not vary between the continuum and the
Brγ line, even though the line is strongly detected in the spectrum,
with a peak intensity 35% above the continuum. This demonstrates that
the line and continuum emission have similar size scales. We assume that
the K-band continuum excess originates in a “puffed-up” inner rim
of the circumstellar disk, and discuss the likely origin of Brγ. Conclusions: .We conclude that this emission most likely arises from
a compact disk wind, launched from a region 0.2-0.5 AU from the star,
with a spatial extent similar to that of the near infrared continuum
emission region, i.e., very close to the inner rim location. Based
on observations collected at the European Southern Observatory, Paranal,
Chile, within the guaranteed time programme 074.A-9025(A).

---------------------------------------------------------
Title: Disk and wind interaction in the young stellar object
<ASTROBJ>MWC 297</ASTROBJ> spatially resolved with AMBER/VLTI
Authors: Malbet, F.; Benisty, M.; de Wit, W. -J.; Kraus, S.; Meilland,
A.; Millour, F.; Tatulli, E.; Berger, J. -P.; Chesneau, O.; Hofmann,
K. -H.; Isella, A.; Natta, A.; Petrov, R. G.; Preibisch, T.; Stee,
P.; Testi, L.; Weigelt, G.; Antonelli, P.; Beckmann, U.; Bresson, Y.;
Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern,
P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.;
Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Zins, G.; Accardo,
M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.;
Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.;
Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé,
A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.;
Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.;
Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez
Utrera, O.; Kamm, D.; Kiekebusch, M.; Le Contel, D.; Le Contel, J. -M.;
Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.;
Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet,
D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier,
C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.;
Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang,
A.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Vakili,
F.; von der Lühe, O.; Valtier, J. -C.; Vannier, M.; Ventura, N.
2007A&A...464...43M Altcode: 2005astro.ph.10350M
The young stellar object <ASTROBJ>MWC 297</ASTROBJ> is an embedded
B1.5Ve star exhibiting strong hydrogen emission lines and a strong
near-infrared continuum excess. This object has been observed with
the VLT interferometer equipped with the AMBER instrument during
its first commissioning run. AMBER/VLTI is currently the only
near infrared interferometer that can observe spectrally dispersed
visibilities. <ASTROBJ>MWC 297</ASTROBJ> has been spatially resolved in
the continuum with a visibility of 0.50+0.08-0.10
as well as in the Brγ emission line where the visibility decreases
to 0.33±0.06. This change in the visibility with wavelength can be
interpreted by the presence of an optically thick disk responsible for
the visibility in the continuum and of a stellar wind traced by the
Brγ emission line and whose apparent size is 40% larger. We validate
this interpretation by building a model of the stellar environment
that combines a geometrically thin, optically thick accretion disk
model consisting of gas and dust, and a latitude-dependent stellar
wind outflowing above the disk surface. The continuum emission and
visibilities obtained from this model are fully consistent with the
interferometric AMBER data. They agree also with existing optical,
near-infrared spectra and other broad-band near-infrared interferometric
visibilities. We also reproduce the shape of the visibilities in the
Brγ line as well as the profile of this line obtained at an higher
spectral resolution with the VLT/ISAAC spectrograph, and those of
the Hα and Hβ lines. The disk and wind models yield a consistent
inclination of the system of approximately 20°. A picture emerges in
which <ASTROBJ>MWC 297</ASTROBJ> is surrounded by an equatorial flat
disk that is possibly still accreting and an outflowing wind that has
a much higher velocity in the polar region than at the equator. The
AMBER/VLTI unique capability of measuring spectral visibilities
therefore allows us for the first time to compare the apparent geometry
of a wind with the disk structure in a young stellar system. Based
on observations collected at the European Southern Observatory, Paranal,
Chile, within the commissioning programme 60.A-9054(A).

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Title: Near-infrared interferometry of <ASTROBJ>η Carinae</ASTROBJ>
with spectral resolutions of 1 500 and 12 000 using AMBER/VLTI
Authors: Weigelt, G.; Kraus, S.; Driebe, T.; Petrov, R. G.; Hofmann,
K. -H.; Millour, F.; Chesneau, O.; Schertl, D.; Malbet, F.; Hillier,
J. D.; Gull, T.; Davidson, K.; Domiciano de Souza, A.; Antonelli,
P.; Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.;
Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi,
F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel,
A.; Tatulli, E.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba,
E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.;
Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.;
Connot, C.; Delboulbé, A.; Feautrier, P.; Ferruzzi, D.; Forveille,
T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.;
Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera,
O.; Kamm, D.; Kiekebusch, M.; Le Contel, D.; Le Contel, J. -M.;
Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars,
G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.;
Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.;
Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.;
Robini, A.; Sacchettini, M.; Schöller, M.; Solscheid, W.; Spang,
A.; Stee, P.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.;
Testi, L.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Vannier,
M.; Ventura, N.; Weis, K.; Wittkowski, M.
2007A&A...464...87W Altcode: 2006astro.ph..9715W
Aims: We present the first NIR spectro-interferometry of the LBV
<ASTROBJ>η Carinae</ASTROBJ>. The observations were performed with
the AMBER instrument of the ESO Very Large Telescope Interferometer
(VLTI) using baselines from 42 to 89 m. The aim of this work is to
study the wavelength dependence of η Car's optically thick wind
region with a high spatial resolution of 5 mas (11 AU) and high
spectral resolution. Methods: The observations were carried
out with three 8.2 m Unit Telescopes in the K-band. The raw data are
spectrally dispersed interferograms obtained with spectral resolutions
of 1500 (MR-K mode) and 12 000 (HR-K mode). The MR-K observations
were performed in the wavelength range around both the He I 2.059 μm
and the Brγ 2.166 μm emission lines, the HR-K observations only in
the Brγ line region. Results: The spectrally dispersed AMBER
interferograms allow the investigation of the wavelength dependence of
the visibility, differential phase, and closure phase of η Car. In
the K-band continuum, a diameter of 4.0±0.2 mas (Gaussian FWHM, fit
range 28-89 m baseline length) was measured for η Car's optically
thick wind region. If we fit Hillier et al. (2001, ApJ, 553, 837)
model visibilities to the observed AMBER visibilities, we obtain 50%
encircled-energy diameters of 4.2, 6.5 and 9.6 mas in the 2.17 μm
continuum, the He I, and the Brγ emission lines, respectively. In
the continuum near the Brγ line, an elongation along a position
angle of 120°±15° was found, consistent with previous VINCI/VLTI
measurements by van Boekel et al. (2003, A&amp;A, 410, L37). We compare
the measured visibilities with predictions of the radiative transfer
model of Hillier et al. (2001), finding good agreement. Furthermore, we
discuss the detectability of the hypothetical hot binary companion. For
the interpretation of the non-zero differential and closure phases
measured within the Brγ line, we present a simple geometric model of
an inclined, latitude-dependent wind zone. Our observations support
theoretical models of anisotropic winds from fast-rotating, luminous hot
stars with enhanced high-velocity mass loss near the polar regions. Based on observations collected at the European Southern Observatory,
Paranal, Chile, within the AMBER guaranteed time programme 074.A-9025
and the VLTI science demonstration programme 074.A-9024.

---------------------------------------------------------
Title: Interferometric data reduction with AMBER/VLTI. Principle,
estimators, and illustration
Authors: Tatulli, E.; Millour, F.; Chelli, A.; Duvert, G.; Acke, B.;
Hernandez Utrera, O.; Hofmann, K. -H.; Kraus, S.; Malbet, F.; Mège,
P.; Petrov, R. G.; Vannier, M.; Zins, G.; Antonelli, P.; Beckmann, U.;
Bresson, Y.; Dugué, M.; Gennari, S.; Glück, L.; Kern, P.; Lagarde,
S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.; Rantakyrö,
F.; Robbe-Dubois, S.; Roussel, A.; Weigelt, G.; Accardo, M.; Agabi,
K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend,
J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse,
J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano de Souza,
A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat,
E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.;
Glentzlin, A.; Heiden, M.; Heininger, M.; Kamm, D.; Kiekebusch, M.;
Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.;
Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias,
P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka,
K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.;
Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller,
M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tallon, M.;
Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe,
O.; Valtier, J. -C.; Ventura, N.
2007A&A...464...29T Altcode: 2006astro.ph..3046T
Aims:In this paper, we present an innovative data reduction method
for single-mode interferometry. It has been specifically developed
for the AMBER instrument, the three-beam combiner of the Very Large
Telescope Interferometer, but it can be derived for any single-mode
interferometer. Methods: The algorithm is based on a direct
modelling of the fringes in the detector plane. As such, it requires
a preliminary calibration of the instrument in order to obtain the
calibration matrix that builds the linear relationship between the
interferogram and the interferometric observable, which is the complex
visibility. Once the calibration procedure has been performed, the
signal processing appears to be a classical least-square determination
of a linear inverse problem. From the estimated complex visibility,
we derive the squared visibility, the closure phase, and the spectral
differential phase. Results: The data reduction procedures have
been gathered into the so-called amdlib software, now available for
the community, and are presented in this paper. Furthermore, each
step in this original algorithm is illustrated and discussed from
various on-sky observations conducted with the VLTI, with a focus on
the control of the data quality and the effective execution of the data
reduction procedures. We point out the present limited performances of
the instrument due to VLTI instrumental vibrations which are difficult
to calibrate. Based on observations collected at the European
Southern Observatory, Paranal, Chile.

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Title: Direct constraint on the distance of γ2 Velorum
from AMBER/VLTI observations
Authors: Millour, F.; Petrov, R. G.; Chesneau, O.; Bonneau, D.;
Dessart, L.; Bechet, C.; Tallon-Bosc, I.; Tallon, M.; Thiébaut,
E.; Vakili, F.; Malbet, F.; Mourard, D.; Antonelli, P.; Beckmann,
U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.;
Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut,
K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Tatulli,
E.; Weigelt, G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba,
E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.;
Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.;
Connot, C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.;
Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.;
Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.;
Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.;
Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel,
J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi,
A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin,
J. -L.; Mouillet, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier,
C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.;
Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang,
A.; Stee, P.; Stefanini, P.; Tasso, D.; Testi, L.; von der Lühe,
O.; Valtier, J. -C.; Vannier, M.; Ventura, N.
2007A&A...464..107M Altcode: 2006astro.ph.10936M
Context: Interferometry can provide spatially resolved observations of
massive star binary systems and their colliding winds, which thus far
have been studied mostly with spatially unresolved observations. Aims: We present the first AMBER/VLTI observations, taken at
orbital phase 0.32, of the Wolf-Rayet and O (WR+O) star binary system
<ASTROBJ>γ2 Velorum</ASTROBJ> and use the interferometric observables
to constrain its properties. Methods: The AMBER/VLTI instrument
was used with the telescopes UT2, UT3, and UT4 on baselines ranging
from 46 m to 85 m. It delivered spectrally dispersed visibilities,
as well as differential and closure phases, with a resolution R=1500
in the spectral band 1.95-2.17 μm. We interpret these data in the
context of a binary system with unresolved components, neglecting in a
first approximation the wind-wind collision zone flux contribution. Results: Using WR- and O-star synthetic spectra, we show that the
AMBER/VLTI observables result primarily from the contribution of the
individual components of the WR+O binary system. We discuss several
interpretations of the residuals, and speculate on the detection of an
additional continuum component, originating from the free-free emission
associated with the wind-wind collision zone (WWCZ), and contributing at
most to the observed K-band flux at the 5% level. Based on the accurate
spectroscopic orbit and the Hipparcos distance, the expected absolute
separation and position angle at the time of observations were 5.1±0.9
mas and 66±15°, respectively. However, using theoretical estimates
for the spatial extent of both continuum and line emission from each
component, we infer a separation of 3.62+0.11-0.30
mas and a position angle of 73+9-11°, compatible
with the expected one. Our analysis thus implies that the binary system
lies at a distance of 368+38-13 pc, in agreement
with recent spectrophotometric estimates, but significantly larger
than the Hipparcos value of 258+41-31 pc. Based on observations collected at the European Southern Observatory,
Paranal, Chile, within the guaranteed time programme 074.A-9025(A).

---------------------------------------------------------
Title: Optical configuration and analysis of the AMBER/VLTI instrument
Authors: Robbe-Dubois, S.; Lagarde, S.; Petrov, R. G.; Lisi,
F.; Beckmann, U.; Antonelli, P.; Bresson, Y.; Martinot-Lagarde,
G.; Roussel, A.; Salinari, P.; Vannier, M.; Chelli, A.; Dugué, M.;
Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Le Coarer, E.; Malbet,
F.; Millour, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Tatulli, E.;
Weigelt, G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba,
E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker,
T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin,
J.; Connot, C.; Delage, L.; Delboulbé, A.; Domiciano de Souza, A.;
Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.;
Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin,
A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.;
Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.;
Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars,
G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Mourard,
D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.;
Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini,
M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stee, P.;
Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Testi, L.;
Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Ventura, N.
2007A&A...464...13R Altcode: 2008arXiv0807.3717R
Aims:This paper describes the design goals and engineering efforts
that led to the realization of AMBER (Astronomical Multi BEam
combineR) and to the achievement of its present performance. Methods: On the basis of the general instrumental concept, AMBER was
decomposed into modules whose functions and detailed characteristics
are given. Emphasis is put on the spatial filtering system, a key
element of the instrument. We established a budget for transmission
and contrast degradation through the different modules, and made the
detailed optical design. The latter confirmed the overall performance
of the instrument and defined the exact implementation of the AMBER
optics. Results: The performance was assessed with laboratory
measurements and commissionings at the VLTI, in terms of spectral
coverage and resolution, instrumental contrast higher than 0.80,
minimum magnitude of 11 in K, absolute visibility accuracy of 1%,
and differential phase stability of 10-3 rad over one minute.

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Title: History, Present Status &amp; Future of Site Testing at Dôme C
Authors: Vernin, J.; Agabi, A.; Aristidi, E.; Azouit, M.; Chadid,
M.; Fossat, E.; Sadibekova, T.; Trinquet, H.; Ziad, A.
2007EAS....25...23V Altcode:
Hereafter we give a brief history of our contribution to astronomical
site testing in Antarctica, at least for the high angular resolution
in the visible range. The decision to undertake the first site testing
at South Pole began one year after a congress organized by French
Académie des Sciences, in year 1992. Indeed, in 1993 a meeting took
place in Chicago with the participation of Peter Gillingham, Al Harper
and Jean Vernin where each one took the respective responsibility of
1) giving a PhD student, 2) the South Pole infrastructure and 3) the
relevant instruments. During winter 1995, thanks to a mast equipped with
micro-thermal sensors, we demonstrated (Marks et al., 1996, A&amp;AS,
118, 1) that the first 30 m of the surface layer was disrupted by
strong optical turbulence. Then, the year after, 15 balloons equipped
with micro-thermal probes were successfully launched from South
Pole. Marks et al. (1999, A&amp;AS, 134, 161) shown that most of the
optical turbulence at South Pole was concentrated within a layer 200 m
thick above the ice level. From this study, it becomes clear that the
noticeable katabatic wind present at South Pole was generating this
huge surface layer and that is why we oriented our astronomical site
characterization toward Dôme C. Our first summer seeing estimations
began in 2000, which demonstrated (Aristidi et al., 2003, A&amp;AS, 406,
L19 &amp; Aristidi et al., 2005, A&amp;A, 444, 651) that, as expected,
the surface wind was much less than at South Pole, and, as a matter of
fact, the seeing was much better, and was even exceptional during the
four hours of the afternoon where a seeing of less than 0.5 arcsec was
measured. In 2005, the Concordia base was first open during the polar
night, and one of us, A. Agabi was able to launch 41 balloons equipped
with micro-thermal sensors. A differential image motion monitor (DIMM)
was also setup with success. At mid winter, Agabi et al. (2006, PASP,
118, 344) showed that most of the optical turbulence came from the
first 30 m surface layer and very little from the rest of the atmosphere
(1.3 arcsec above 8.5 m and 0.37 arcsec above 30 m).

---------------------------------------------------------
Title: Choosing Dome C, Antarctic Plateau as Future Astronomical
Observatory
Authors: Sadibekova, T.; Fossat, E.; Vernin, J.; Agabi, A.; Aristidi,
E.; Azouit, M.; Chadid, M.; Trinquet, H.; Genthon, C.; Krinner, G.;
Sarazin, M.
2007EAS....25...69S Altcode:
In this paper we present year-round climatological analysis made
from radio-sounding measurements and ECMWF Data. And we end up with
a generalized conclusion (scientific aspect) from statistical results
of site-testing at Concordia concerning the feasibility of the future
astronomical exploitation of Dome C.

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Title: Dome C: An exceptional site for solar observations .
Authors: Arnaud, J.; Faurobert, M.; Fossat, E.
2007MmSAI..78..105A Altcode:
Dome C, on the Antarctica plateau, may be the best site on Earth
for astronomy, thanks to outstanding image quality and very pure and
cold atmosphere. This is of particular interest for solar physics,
namely for very high-resolution studies of the solar surface and
for magnetometry of the innermost solar corona. Here we review Dome
C unique atmospheric properties and present two projects aimed at
quantitatively qualify this site for solar observations.

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Title: GIVRE: A Protection Against Frost Deposit on Polar Instruments
Authors: Durand, G.; Cadelis, L.; Minier, V.; Veyssière, C.; Walter,
C.; Pierre, A.; Agabi, A.; Fossat, E.; Jeanneaux, F.
2007EAS....25...77D Altcode:
The CEA, in coordination with IPEV and LUAN, will prepare an experiment
to study frost formation on surfaces in radiative cooling in the
winter. This experiment has been shipped to be installed at Concordia
before the 2007 winter period. It will be controlled from Concordia
winterover personal, through PC server that will locally archive data
from WEBcams and several local heat regulators. This experiment will be
used to give recipes on the way to compensate with heaters the radiative
cooling from the sky and maintain instrument surfaces at temperature
just above icing conditions. The individual regulators proposed in
this experiment will be usable as standalone ice protection systems
for existing and future telescopes.

---------------------------------------------------------
Title: Stella Antarctica An I.P.Y. Programme Towards an International
Astronomical Observatory at Dome C, Antarctica
Authors: Fossat, E.
2007EAS....25...19F Altcode:
This paper describes STELLA ANTARCTICA, one of the two astronomical
projects sponsored by the International Polar Year.

---------------------------------------------------------
Title: The DynaMICS perspective
Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies,
S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.;
Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.;
Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat,
E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.;
Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes,
I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.;
Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.;
Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.;
Thompson, M.; Vauclair, S.; Zahn, J. P.
2006ESASP.624E..24T Altcode: 2006soho...18E..24T
No abstract at ADS

---------------------------------------------------------
Title: 6 years of site testing at Concordia
Authors: Fossat, E. G.
2006IAUSS...7E...3F Altcode:
The Concordiastro site testing programme has been started in November,
2000. Six summer seasons have already been extensively tested, and the
second winter is now under way. The statistical astronomical properties
of the local sky are now well known. They will be reviewed, as well
as those additional ionformations that still require more studies.

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Title: Atmospheric scintillation at Dome C, Antarctica: implications
for photometry and astrometry
Authors: Kenyon, S.; Lawrence, J.; Ashley, M. C. B.; Storey, J. W. V.;
Tokovinin, A.; Fossat, E.
2006IAUSS...7E..30K Altcode:
Night-time turbulence profiles of the atmosphere above Dome C,
Antarctica, were measured during 2004, using a MASS instrument. We
compare this data with turbulence profiles above Cerro Tololo and
Cerro Pachon, also measured with a MASS, and find, with the exception
of the owest layer, that Dome C has significantly less turbulence. In
addition, the integrated at turbulence 16 km above Dome C is always
less than the median values at the two Chilean sites. Using average
wind speed profiles, we assess the photometric noise produced by
scintillation, and the atmospheric contribution to the error budget
in narrow angle differential astrometry. In comparison with the
two mid-latitude sites in Chile, Dome C offers a potential gain of
about 3.6 in both photometric precision (for long integrations) and
narrow-angle astrometry precision. Although the data from Dome C cover
a fairly limited time frame, they lend strong support to expectations
that Dome C will offer significant advantages for photometric and
astrometric studies.

---------------------------------------------------------
Title: Site Testing At Dome C: History, Present Status &amp; Futur
Authors: Vernin, J.; Agabi, A.; Aristidi, E.; Azouit, M.;
Chadid-Vernin, M.; Fossat, E.; Sadibekova, T.; Ziad, A.
2006IAUSS...7E..17V Altcode:
Here we present why we decided to undertake a site characterization
at Dome C, Antarctica following a first step made at South Pole. It
was clear that poor seeing measured at South Pole was mainly due to
ground catabatic wind interacting with strong vertical temperature
(refractive index) gradient. Thus, we though to move to Dome C where
no catabatic wind is expected. We will recall the history of this
long adventure. Then we will present the more recent results which
concern daytime observations as well as nighttime observations, as
measured by DIMM, balloons, GSM and SSS. From this database and the
very special vertical distribution fo the optical turbulence at Dome C,
we will present some strong implications for High Angular Resolution
astronomy at Dome C.

---------------------------------------------------------
Title: Scientific Objectives of the Novel Formation Flying Mission
Aspiics
Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies,
S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.;
Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.;
Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat,
E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.;
Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes,
I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.;
Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.;
Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.;
Thompson, M.; Vauclair, S.; Zahn, J. P.
2006ESASP.617E.164L Altcode: 2006soho...17E.164L
No abstract at ADS

---------------------------------------------------------
Title: The EUV Variability Experiment (EVE) on the Solar Dynamics
Observatory (SDO): Science Plan and Instrument Overview
Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies,
S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.;
Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.;
Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat,
E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.;
Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes,
I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.;
Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.;
Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.;
Thompson, M.; Vauclair, S.; Zahn, J. P.
2006ESASP.617E.165W Altcode: 2006soho...17E.165W
No abstract at ADS

---------------------------------------------------------
Title: The Dynamics Project
Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies,
S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.;
Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.;
Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat,
E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.;
Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes,
I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.;
Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.;
Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.;
Thompson, M.; Vauclair, S.; Zahn, J. P.
2006ESASP.617E.162T Altcode: 2006soho...17E.162T
No abstract at ADS

---------------------------------------------------------
Title: Atmospheric Scintillation at Dome C, Antarctica: Implications
for Photometryand Astrometry
Authors: Kenyon, S. L.; Lawrence, J. S.; Ashley, M. C. B.; Storey,
J. W. V.; Tokovinin, A.; Fossat, E.
2006PASP..118..924K Altcode: 2006astro.ph..4538K
We present low-resolution turbulence profiles of the atmosphere above
Dome C, Antarctica, measured with the MASS instrument during 25 nights
in 2004 March-May. Except for the lowest layer, Dome C has significantly
less turbulence than Cerro Tololo and Cerro Pachón. In particular, the
integrated turbulence at 16 km is always less than the median values at
the two Chilean sites. From these profiles we evaluate the photometric
noise produced by scintillation, and the atmospheric contribution to
the error budget in narrow-angle differential astrometry. In comparison
with the two midlatitude sites in Chile, Dome C offers a potential gain
of about 3.6 in both photometric precision (for long integrations) and
narrow-angle astrometry precision. These gain estimates are preliminary,
being computed with average wind-speed profiles, but the validity of
our approach is confirmed by independent data. Although the data from
Dome C cover a fairly limited time frame, they lend strong support
to expectations that Dome C will offer significant advantages for
photometric and astrometric studies.

---------------------------------------------------------
Title: Solar FLAG hare and hounds: on the extraction of rotational
p-mode splittings from seismic, Sun-as-a-star data
Authors: Chaplin, W. J.; Appourchaux, T.; Baudin, F.; Boumier, P.;
Elsworth, Y.; Fletcher, S. T.; Fossat, E.; García, R. A.; Isaak,
G. R.; Jiménez, A.; Jiménez-Reyes, S. J.; Lazrek, M.; Leibacher,
J. W.; Lochard, J.; New, R.; Pallé, P.; Régulo, C.; Salabert, D.;
Seghouani, N.; Toutain, T.; Wachter, R.
2006MNRAS.369..985C Altcode: 2006MNRAS.tmp..515C; 2006astro.ph..6748C
We report on results from the first solar Fitting at Low-Angular
degree Group (solar FLAG) hare-and-hounds exercise. The group
is concerned with the development of methods for extracting the
parameters of low-l solar p-mode data (`peak bagging'), collected by
Sun-as-a-star observations. Accurate and precise estimation of the
fundamental parameters of the p modes is a vital pre-requisite of all
subsequent studies. Nine members of the FLAG (the `hounds') fitted
an artificial 3456-d data set. The data set was made by the `hare'
(WJC) to simulate full-disc Doppler velocity observations of the
Sun. The rotational frequency splittings of the l = 1, 2 and 3 modes
were the first parameter estimates chosen for scrutiny. Significant
differences were uncovered at l = 2 and 3 between the fitted splittings
of the hounds. Evidence is presented that suggests this unwanted bias
had its origins in several effects. The most important came from the
different way in which the hounds modelled the visibility ratio of
the different rotationally split components. Our results suggest that
accurate modelling of the ratios is vital to avoid the introduction of
significant bias in the estimated splittings. This is of importance
not only for studies of the Sun, but also of the solar analogues
that will be targets for asteroseismic campaigns. Solar FLAG
URL: http://bison.ph.bham.ac.uk/~wjc/Research/FLAG.html E-mail:
wjc@bison.ph.bham.ac.uk ‡ George Isaak passed away in 2005 June
5, prior to the completion of this work. He is greatly missed by us all.

---------------------------------------------------------
Title: Jovian seismology: preliminary results of the SYMPA instrument
Authors: Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Jeanneaux,
F.; Alvarez, M.; Reyes, M.; Valtier, J. C.; Fossat, E.; Palle, P. L.;
Belmonte, J. C.; Gelly, B.
2006sf2a.conf..403G Altcode:
Jupiter's internal structure is poorly known (Guillot et
al. 2004). Seismology is a powerful tool to investigate the internal
structure of planets and stars, by analyzing how acoustic waves
propagate. Mosser (1997) and Gudkova &amp; Zarkhov (1999) showed
that the detection and the identification of non-radial modes up to
degree ℓ=25 can constrain strongly the internal structure. SYMPA is
a ground-based network project dedicated to the Jovian oscillations
(Schmider et al. 2002). The instrument is composed of a Mach-Zehnder
interferometer producing four interferograms of the planetary
spectrum. The combination of the four images in phase quadrature allows
the reconstruction of the incident light phase, which is related to
the Doppler shift generated by the oscillations. Two SYMPA instruments
were built at the Nice university and were used simultaneously during
two observation campaigns, in 2004 and 2005, at the San Pedro Martir
observatory (Mexico) and the Teide observatory (Las Canarias). We will
present for the first time the data processing and the preliminary
results of the experiment.

---------------------------------------------------------
Title: First Whole Atmosphere Nighttime Seeing Measurements at Dome
C, Antarctica
Authors: Agabi, A.; Aristidi, E.; Azouit, M.; Fossat, E.; Martin,
F.; Sadibekova, T.; Vernin, J.; Ziad, A.
2006PASP..118..344A Altcode: 2005astro.ph.10418A
We report site-testing results obtained in the nighttime during
the polar autumn and winter at Dome C. These results were collected
during the first Concordia winterover by A. Agabi. They are based on
seeing and isoplanatic angle monitoring, as well as in situ balloon
measurements of the refractive index structure constant profiles
C2n(h). Atmosphere is divided into two regions:
(1) a 36 m high surface layer responsible for 87% of the turbulence,
and (2) a very stable free atmosphere above, with a median seeing of
0.36" +/- 0.19" at an elevation of h=30 m. The median seeing measured
with a differential image motion monitor placed on top of an 8.5 m
high tower is 1.3" +/- 0.8".

---------------------------------------------------------
Title: GOLF-NG spectrometer, a space prototype for studying the
dynamics of the deep solar interior
Authors: Turck-Chièze, Sylvaine; Carton, Pierre-Henri; Ballot,
Jérome; Barrière, Jean-Christophe; Daniel-Thomas, Philippe; Delbart,
Alain; Desforges, Daniel; Garcia, Rafaël A.; Granelli, Rémi; Mathur,
Savita; Nunio, François; Piret, Yves; Pallé, Pere L.; Jiménez,
Antonio J.; Jiménez-Reyes, Sebastian J.; Robillot, Jean Maurice;
Fossat, Eric; Eff-Darwich, Antonio. M.; Gelly, Bernard
2006AdSpR..38.1812T Altcode: 2005astro.ph.10753T
The GOLF-NG (Global Oscillations at Low Frequency New Generation)
instrument is devoted to the search for solar gravity and acoustic
modes, and also chromospheric modes from space. This instrument which
is a successor to GOLF/SOHO will contribute to improve our knowledge
of the dynamics of the solar radiative zone. It is a 15 points resonant
scattering spectrometer, working on the D1 sodium line. A ground-based
prototype is under construction to validate the difficult issues. It
will be installed at the Teide Observatory, on Tenerife in 2006 to
analyse the separation of the effects of the magnetic turbulence of
the line from the solar oscillations. We are prepared to put a space
version of this instrument including a capability of identification of
the modes, in orbit during the next decade. This instrument should be
included in the ILWS program as it offers a key to the improvement of
our knowledge of the solar core in combination with observations from
SDO and PICARD. We hope to determine the core rotation and magnetic
field, through precise measurements of oscillation mode frequency
splittings. Understanding the magnetic field of the radiative zone
is important for progress in the study of solar activity sources,
an important player for the long-term Sun-Earth relationship.

---------------------------------------------------------
Title: Site testing in winter at Dome C
Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Azouit, M.; Vernin,
J.; Sadibekova, T.; Travouillon, T.; Ziad, A.; Martin, F.
2005sf2a.conf...45A Altcode:
We present site testing results obtained in night-time during
the polar winter at Dome C. These results were collected during
the first Concordia winterover by A. Agabi. They are based upon
seeing and isoplanatic angle monitoring, as well as in-situ balloon
measurements of the refractive index structure constant profiles
Cn2(h). Atmosphere is divided into two regions:
(i) a 36 m high surface layer responsible of 87% of the turbulence
and (ii) a very stable free atmosphere above with a median seeing of
0.36±0.19 arcsec at an elevation of h=30m. The median seeing measured
with a DIMM placed on top of a 8.5 m high tower is 1.3±0.8 arcsec.

---------------------------------------------------------
Title: Working group report on Asteroseismology and stellar activity
from Dome C
Authors: Bouchy, F.; Mosser, B.; Catala, C.; Appourchaux, T.; Bouvier,
J.; Chadid, M.; Donati, J. F.; Fossat, E.; Schmider, F. X.; Thevenin,
F.; Vauclair, G.
2005sf2a.conf..329B Altcode:
This paper presents the conclusions of the working group for stellar
physics observations at the Dome-C station in Antarctica. It summarizes
the advantages of Dome-C for asteroseismology and stellar activity,
identifies strategies and possible instrumental projects to be conducted
there, and concludes with recommendations for the development of stellar
observations. The conclusions are based on the fact that continuous
observations over several weeks or months without breaks due to the
diurnal cycle are fundamental for programs of stellar physics and
especially for asteroseismology and stellar activity. Therefore, Dome-C
appears to be a unique ground-based site offering ideal conditions
for continuous observations.

---------------------------------------------------------
Title: Site testing in summer at Dome C, Antarctica
Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Azouit, M.; Martin,
F.; Sadibekova, T.; Travouillon, T.; Vernin, J.; Ziad, A.
2005A&A...444..651A Altcode: 2005astro.ph..7475A
We present summer site testing results based on DIMM data obtained
at Dome C, Antarctica. These data were collected on the bright
star Canopus during two 3-months summer campaigns in 2003-2004 and
2004-2005. We performed continuous monitoring of the seeing and the
isoplanatic angle in the visible. We found a median seeing of 0.54”
and a median isoplanatic angle of 6.8”. The seeing appears to have
a deep minimum around 0.4” almost every day in late afternoon.

---------------------------------------------------------
Title: The Concordia Station on the Antarctic Plateau: The Best Site
on Earth for the 21st Century Astronomers
Authors: Fossat, Eric
2005JApA...26..349F Altcode:
On the Antarctic plateau, a joint project of French and Italian polar
programmes is nearing completion: the Concordia station will be open
for winter-over operation in 2005. The high altitude and high latitude
of this site, the exceptionally cold, clear and stable atmosphere,
its incredible astronomical seeing, the almost indefinitely flat snow
surface and the not-so- difficult access make this site the most
promising on Earth for future ground-based astronomical projects
in various fields, including long term photometry, infrared high
sensitivity imaging and high angular resolution and high contrast
imaging.

---------------------------------------------------------
Title: An analysis of temperatures and wind speeds above Dome C,
Antarctica
Authors: Aristidi, E.; Agabi, K.; Azouit, M.; Fossat, E.; Vernin,
J.; Travouillon, T.; Lawrence, J. S.; Meyer, C.; Storey, J. W. V.;
Halter, B.; Roth, W. L.; Walden, V.
2005A&A...430..739A Altcode:
A good astronomical site must fulfill several criteria including low
atmospheric turbulence and low wind speeds. It is therefore important
to have a detailed knowledge of the temperature and wind conditions of
a location considered for future astronomical research. Antarctica has
unique atmospheric conditions that have already been exploited at the
South Pole station. Dome C, a site located on a local maximum of the
Antarctic plateau, is likely to have even better conditions. In this
paper we present the analysis of two decades of wind speed measurements
taken at Dome C by an automated weather station (AWS). We also present
temperature and wind speed profiles taken over four Antarctic summers
using balloon-borne weather sondes. We will show that as well as having
one of the lowest average wind speed ever recorded at an existing
or potential observatory, Dome C also has an extremely stable upper
atmosphere and a very low inversion layer.

---------------------------------------------------------
Title: Asteroseismology and Stellar Pulsation feasibility at Dome C
Authors: Chadid, M.; Vernin, J.; Fossat, E.
2005EAS....14..281C Altcode:
Four site testing campaigns have already been conducted at Dome
C during the local summers. A very reasonable extrapolation of the
knowledge acquired on the atmospheric properties shows that broad band
photometry could be exploited there for developing asteroseismology
of many pulsating stars, including the solar-type ones, despite their
very small oscillation amplitudes. This paper focuses more specifically
on the usual limiting factor in photometry which is the scintillation.

---------------------------------------------------------
Title: JISCO: Jovian Interferometric Seismometer at Concordia
Observatory
Authors: Schmider, F. X.; Jacob, C.; Fossat, E.; Abe, L.; Gay, J.;
Valtier, J. -C.; Guillot, T.; Provost, J.; Mosser, B.; Gaulme, P.
2005EAS....14..285S Altcode:
Seismology is the only way to investigate the internal structure
of the giant planets, with a lot of scientific implications such
as high pressure physics and huge constraints on the scenario of
solar system formation. As compared to other existing possibilities
(ground based network, spacecraft), seismology of Jupiter will take
a maximum benefit from the peculiarities of the Concordia station as
an astronomical observatory. Indeed, the continuous temporal coverage
for all the winter season, and the quality of the atmospheric seeing,
are crucial parameters for this program. The jovian seismometer
SYMPA, already used for network observations, is perfectly suitable
for Dome C conditions. With the already existing small telescopes
deployed in the frame of site testing program, seismology of Jupiter
will constitute a excellent intermediate project with high scientific
return, before the installation of large telescopes. In a second step,
such an instrument could be a first light instrument for a 1.5 m class
automatic telescope, which is to be developed as an individual stone
for a large interferometer. With this diameter, the same scientific
program on Saturn could also be achieved.

---------------------------------------------------------
Title: Asteroseismology
Authors: Fossat, E.
2005EAS....14..121F Altcode:
Regarding its seeing properties or its photometric quality as well, the
Dome C Concordia site is presented as being an intermediate solution
between space and a good mountain observatory. This statement still
needs somewhat further night time confirmation. If really true, as is
more and more expected after the preliminary site testing campaigns
(Aristidi et al. 2004; Storey et al. 2004), this opens extremely
promising prospects for asteroseismology of solar-type stars, and also
of any kind of star for which a continuous observation much longer
than 12 hours is an important requirement.

---------------------------------------------------------
Title: Site testing study based on weather balloons measurements
Authors: Aristidi, E.; Agabi, A.; Azouit, M.; Fossat, E.; Vernin, J.;
Sadibekova, T.; Travouillon, T.; Lawrence, J. S.; Halter, B.; Roth,
W. L.; Walden, V. P.
2005EAS....14..227A Altcode: 2018arXiv181200028A
We present wind and temperature profiles at Dome C measured during
the polar summer by balloon born sonds. Data from 197 flights have
been processed for 4 campaigns between 2000 and 2004. We show the
exceptionnal wind conditions at Dome C: averaged ground wind speed is
3.6 m s-1. We noticed in mid-november the presence of high
altitude strong winds (40 m s-1) probably due to the polar
vortex which disappear in summer. These winds seem to have no effect on
seeing measurements made with a DIMM at the same period. Temperature
profiles exhibit a minimum at height 5500 m (over the snow surface)
that defines the tropopause. Surface layer temperature profile has
negative gradient in the first 50 m above ground in the afternoon and a
strong inversion layer (5°C over 50 m) around midnight. Wind profiles
are compared with other astronomical sites, and with a meteorological
model from Meteo France.

---------------------------------------------------------
Title: Setting the Scene
Authors: Fossat, E.
2005EAS....14....1F Altcode:
The Concordia station on the Antarctica plateau will open very soon
its winter-over activities. Astronomy is among the top priorities,
because of the unique qualities that are being demonstrated step by
step by the site testing programmes Concordiastro and Aastino.

---------------------------------------------------------
Title: Daytime site testing at Dome C: Results of 2003 2004 campaign
Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Travouillon, T.; Azouit,
M.; Vernin, J.; Ziad, A.; Martin, F.; Robuchon, G.
2005EAS....14...13A Altcode:
We present results of daytime site testing at Dome C in summer
2003 2004. Daytime seeing has been monitored during 2 1/2 months
using a DIMM on the bright star Canopus, giving median value of 0.54
arcsec. An every-day best seeing period has been observed around 5 pm
with seeing around 0.3 arcsec. First isoplanatic angle measurements,
based on stellar scintillation, were also performed during the month
of January 2004, and have given median value of 6.8 arcsec.

---------------------------------------------------------
Title: KEOPS: towards exo-Earths from Dome C of Antarctica
Authors: Vakili, F.; Aristidi, E.; Schmider, F. X.; Jankov, S.;
Fossat, E.; Abe, L.; Domiciano, A.; Belu, A.; Agabi, A.; Daban,
J. -B.; Robbe-Dubois, S.; Petrov, R.; Vernin, J.; Ziad, A.; Lopez, B.
2005EAS....14..211V Altcode:
This paper describes a coronagraphic nulling interferometer called
KEOPS (Kiloparsec Explorer for Optical Planet Search) to be placed
on the Dome C plateau of Antarctica. KEOPS is an interferometric
array of 39 1m 2m telescopes spread over kilometric baselines and
operated in the thermal IR region. It could search and characterize all
potential exoEarths within the 1 kpc diameter region observable from
Dome C. We argue that even in the very difficult operation conditions
of Antarctica, such a facility can compete at a much lower cost with
the non-zero risk space missions, both for for ExPNs search and their
spectroscopic characterization plus sub-mas snap-shot imaging of
galactic and extra-galactic compact sources.

---------------------------------------------------------
Title: Flag Hare-And Exercise: on the Extraction of Sectoral Mode
Splittings from Full-Disc Sun-As Data
Authors: Chaplin, W. J.; Appourchaux, T.; Baudin, F.; Boumier, P.;
Elsworth, Y.; Fletcher, S. T.; Fossat, E.; García, R. A.; Isaak,
G. R.; Jiménez, A.; Jiménez-Reyes, S. J.; Lazrek, M.; Lochard, J.;
New, R.; Pallé, P.; Régulo, C.; Salabert, D.; Toutain, T.
2004ESASP.559..356C Altcode: 2004soho...14..356C
No abstract at ADS

---------------------------------------------------------
Title: GOLF Low Degree P-Mode Frequencies and Splittings Accurately
Corrected for the Solar Magnetic Activity
Authors: Lazrek, M.; Fossat, E.; Grec, G.; Renaud, C.; Schmider, F. X.
2004ESASP.559..528L Altcode: 2004soho...14..528L
No abstract at ADS

---------------------------------------------------------
Title: The Antarctic planet interferometer
Authors: Swain, Mark R.; Walker, Christopher K.; Traub, Wesley A.;
Storey, John W.; Coudé du Foresto, Vincent; Fossat, Eric; Vakili,
Farrokh; Stark, Anthony A.; Lloyd, James P.; Lawson, Peter R.; Burrows,
Adam S.; Ireland, Michael; Millan-Gabet, Rafael; van Belle, Gerard T.;
Lane, Benjamin F.; Vasisht, Gautam; Travouillon, Tony
2004SPIE.5491..176S Altcode:
The Antarctic Planet Interferometer is a concept for an instrument
designed to detect and characterize extrasolar planets by exploiting
the unique potential of the best accessible site on earth for thermal
infrared interferometry. High-precision interferometric techniques
under development for extrasolar planet detection and characterization
(differential phase, nulling and astrometry) all benefit substantially
from the slow, low-altitude turbulence, low water vapor content,
and low temperature found on the Antarctic plateau. At the best of
these locations, such as the Concordia base being developed at Dome
C, an interferometer with two-meter diameter class apertures has the
potential to deliver unique science for a variety of topics, including
extrasolar planets, active galactic nuclei, young stellar objects,
and protoplanetary disks.

---------------------------------------------------------
Title: Gravity Modes with a Resonant Scattering Spectrophotometer
Authors: Turck-Chièze, S.; Garcia, R. A.; Couvidat, S.; Ballot, J.;
Jiménez-Reyes, S. J.; Fossat, E.; Gelly, B.; Mathur, S.; Nghiem,
P. A. P.; Pallé, P.; Robillot, Jm.; GOLF-Ng Technical Team
2004ESASP.559...85T Altcode: 2004soho...14...85T
No abstract at ADS

---------------------------------------------------------
Title: KEOPS: Kiloparsec Explorer for Optical Planet Search, a
direct-imaging optical array at Dome C of Antarctica
Authors: Vakili, Farrokh; Belu, Adrian; Aristidi, Eric; Fossat, Eric;
Maillard, A.; Abe, Lyu; Agabi, Karim; Vernin, Jean; Baptiste Daban,
Jean; Hertmanni, Wilfried; Schmider, Francois-Xavier; Assus, Pierre;
Coudé du Foresto, Vincent; Swain, Mark R.
2004SPIE.5491.1580V Altcode:
Recent site seeing testing campaigns conducted by our team from
University of Nice1 show that Dome C represents the best site on Earth
for astronomical high angular resolution (HAR) observations at optical
and IR wavelengths. The dramatic gain over relevant HAR parameters
r0, L0, θ0 and τ0, added to very low temperatures during the polar
winter nights (-70°C), the dry atmosphere and the possibility of
continuous observations during several nights make Dome C the ideal
site for deploying a kilometric optical interferometer before the
2015 horizon. Here we describe the concept of Kiloparsec Explorer
for Optical Planet Search (KEOPS) that is studied by our group at
LUAN. KEOPS is an interferometric array of 36 off-axis telescopes,
each 1.5m in diameter. Its kilometric baselines open sub-mas snap-shot
imaging possibilities to detect and characterize extra-solar planetary
systems, especially exo-Earths out to 300 parsecs from the visible
to the thermal IR. KEOPS can be considered as a DARWIN/TPF challenger
but at a much lower cost.

---------------------------------------------------------
Title: About the rotation of the solar radiative interior
Authors: García, R. A.; Corbard, T.; Chaplin, W. J.; Couvidat, S.;
Eff-Darwich, A.; Jiménez-Reyes, S. J.; Korzennik, S. G.; Ballot,
J.; Boumier, P.; Fossat, E.; Henney, C. J.; Howe, R.; Lazrek, M.;
Lochard, J.; Pallé, P. L.; Turck-Chièze, S.
2004SoPh..220..269G Altcode:
In the modern era of helioseismology we have a wealth of high-quality
data available, e.g., more than 6 years of data collected by the various
instruments on board the SOHO mission, and an even more extensive
ground-based set of observations covering a full solar cycle. Thanks
to this effort a detailed picture of the internal rotation of the Sun
has been constructed. In this paper we present some of the actions
that should be done to improve our knowledge of the inner rotation
profile discussed during the workshop organized at Saclay on June 2003
on this topic. In particular we will concentrate on the extraction of
the rotational frequency splittings of low- and medium-degree modes
and their influence on the rotation of deeper layers. Furthermore,
for the first time a full set of individual |m|-component rotational
splittings is computed for modes ℓ≤4 and 1&lt;ν&lt;2 mHz, opening
new studies on the latitudinal dependence of the rotation rate in the
radiative interior. It will also be shown that these splittings have
the footprints of the differential rotation of the convective zone
which can be extremely useful to study the differential rotation of
other stars where only these low-degree modes will be available.

---------------------------------------------------------
Title: Solar gravity modes: the present and future
Authors: Turck-Chièze, S.; Garcià, R.; Fossat, E.; Gelly, B.; Palle,
P.; Robillot, Jm; Golf-Ng
2004cosp...35.3949T Altcode: 2004cosp.meet.3949T
Gravity modes are the best probes to study the solar radiative zone,
in particular the nuclear core and to follow its potential variability
with time and latitude. Nevertheless, their amplitude is small and
the solar noise particularly high in the range of frequency where
they stand (below 500 μ Hz). It is why they are looked for more than
20 years and actively serached with GOLF and MDI instruments aboard
SoHO which offers the best conditions of observation. Some candidates
(Turck-Chièze et al. 2004) have been identified in the GOLF instrument,
during the period of low solar activity thanks to an original research
of multiplets corresponding to surface amplitudes of about 2mm/s. The
examination of the interesting frequency range (100 to 400 μ Hz) will
be pursued up to the end of the SoHO mission scheduled for 2007. Today
our knowledge of the radiative zone is due to acoustic modes. Recent
clear progress is due to the detection of modes less influenced by
the sun activity, in the range 400-1600 μ Hz. The sound speed is
determined down to 0.06 Ro with a resolution of 3%. This profile
is used to improve the solar model and its deviations from a static
vision. The rotation profile is now clearly established down to the
limit of the core and its rigidity can only be explained by invoking
a magnetic field effect. We present here GOLF-NG (Turck-Chièze et
al., 2000) built by a French Spanish collaboration to improve g-mode
detection. Based on the Doppler velocity method using a resonant
spectrometer with a 16 channels on the sodium line, the main objective
of GOLF-NG is to contribute to get an MHD picture of the Sun to better
understand the influence of the Sun on earth climate, in improving
the detection by a factor 10 in decreasing the solar noise thanks
to a variable magnet. Consequently, the physical information will be
extracted at different heights in the atmosphere. A prototype will be
installed in 2005 in Tenerife. Then a spatial version will be available
for taking place in one project of the ILWS mission. Turck-Chièze,
S., Robillot, J.M., Dzitko, H ., Boumier, P., Decaudin, M., Gabriel,
A.H., Garcia, R.A., Grec, G., Pallé, P.L., Renaud, C., Schmidt, D.,
2000, ESA SP-464, 331; Turck-Chieze, S., Garcia, R.A., Couvidat, S.,
et al., 2004, ApJ, vol 604,

---------------------------------------------------------
Title: The Concordia station on Antarctica plateau: the best site
on Earth for High Angular Resolution and High Contrast Imaging
Authors: Fossat, E.; Aristidi, E.; Agabi, K.
2004EAS....12..125F Altcode:
On the Antarctica plateau, a joint project of french and italian polar
programmes in just near completion: the Concordia station will be open
for winterover operation in 2005. The high altitude and high latitude
of this site, the exceptionally cold, clear and stable atmosphere,
the almost indefinitely flat snow surface and the not so difficult
access make this site the most promising on Earth for future ground
based astronomical projects in various fields, including High Angular
Resolution and High Contrast Imaging.

---------------------------------------------------------
Title: Solar gravity modes: the present and future
Authors: Turck-Chièze, S.; Garcià, R.; Fossat, E.; Gelly, B.; Palle,
P.; Robillot, Jm
2004cosp...35.3946T Altcode: 2004cosp.meet.3946T
Gravity modes are the best probes to study the solar radiative zone,
in particular the nuclear core and to follow its potential variability
with time and latitude. Nevertheless, their amplitude is small and
the solar noise particularly high in the range of frequency where
they stand (below 500 μ Hz). It is why they are looked for more than
20 years and actively serached with GOLF and MDI instruments aboard
SoHO which offers the best conditions of observation. Some candidates
(Turck-Chièze et al. 2004) have been identified in the GOLF instrument,
during the period of low solar activity thanks to an original research
of multiplets corresponding to surface amplitudes of about 2mm/s. The
examination of the interesting frequency range (100 to 400 μ Hz) will
be pursued up to the end of the SoHO mission scheduled for 2007. Today
our knowledge of the radiative zone is due to acoustic modes. Recent
clear progress is due to the detection of modes less influenced by the
sun activity, in the range 400-1600 μ Hz. The sound speed is determined
down to 0.06 Ro with a resolution of 3%. This profile is used to improve
the solar model and its deviations from a static vision. The rotation
profile is now clearly established down to the limit of the core and its
rigidity can only be explained by invoking a magnetic field effect. We
present here GOLF-NG (Turck-Chièze et al., 2000) built by a French
Spanish collaboration to improve g-mode detection. Based on the Doppler
velocity method using a resonant spectrometer with a 16 channels on
the sodium line, the main objective of GOLF-NG is to contribute to
get an MHD picture of the Sun to better understand the influence of
the Sun on earth climate, in improving the detection by a factor 10 in
decreasing the solar noise thanks to a variable magnet. Consequently,
the physical information will be extracted at different heights in the
atmosphere. A prototype will be installed in 2005 in Tenerife. Then a
spatial version will be available for taking place in one project of the
ILWS mission. Turck-Chièze, S., Robillot, J.M., Dzitko, H ., Boumier,
P., Decaudin, M., Gabriel, A.H., Garcia, R.A., Grec, G., Pallé, P.L.,
Renaud, C., Schmidt, D., 2000, ESA SP-464, 331; Turck-Chièze, S.,
Garcia, R.A., Couvidat, S., et al., 2004, ApJ, vol 604,

---------------------------------------------------------
Title: Solar p modes in 10 years of the IRIS network
Authors: Salabert, D.; Fossat, E.; Gelly, B.; Kholikov, S.; Grec,
G.; Lazrek, M.; Schmider, F. X.
2004A&A...413.1135S Altcode:
IRIS data (the low degree ℓ≤ 3 helioseismology network) have
been analysed for the study of p-mode parameters variability over the
falling phase of the solar activity cycle 22 and the rising phase of
the solar activity cycle 23. The IRIS duty cycle has been improved
by the so-called “repetitive music method”, a method of partial
gap filling. We present in this paper an analysis of the dependence
of p-mode frequencies and linewidths with frequency and with solar
magnetic activity. We confirm also the periodicity of about 70 μHz
of the high-frequency pseudo modes, with a much reduced visibility
during the phase of higher activity.

---------------------------------------------------------
Title: The Antarctic Planet Interferometer
Authors: Swain, M.; Lloyd, J.; Traub, W.; Walker, C.; Stark, A.;
Lawson, P.; Storey, J.; Coudé du Foresto, V.; Fossat, E.; Ireland,
M.; Burrows, A.; Vakili, F.
2003AAS...203.3815S Altcode: 2003BAAS...35.1262S
The Antarctic Planet Interferometer is a concept designed to
detect and characterize extrasolar planets by exploiting the unique
potential of the best accessible site on Earth for thermal infrared
interferometry. High-precision interferometric techniques under
development for extrasolar planet detection and characterization
(differential phase, nulling and astrometry) all benefit substantially
from the slow, low-altitude turbulence, low water vapor content,
and low temperatures found on the Antarctic plateau. At the best of
these locations, such as the Concordia base being developed at dome
C, an interferometer with two-meter diameter class apertures has the
potential to deliver unique science for a variety of topics, including
extrasolar planets, active galactic nuclei, young stellar objects,
and protoplanetary disks.

---------------------------------------------------------
Title: Antarctic site testing: First daytime seeing monitoring at
Dome C
Authors: Aristidi, E.; Agabi, A.; Vernin, J.; Azouit, M.; Martin,
F.; Ziad, A.; Fossat, E.
2003A&A...406L..19A Altcode:
The first astronomical seeing monitoring has been made with a DIMM
instrument at the Antarctic plateau site of Dome C in December, 2002
on the bright star Canopus (alpha Eri) during the daytime. In these
far from optimal conditions, a median seeing value of 1.20 arcsec
as been obtained, with extended periods better than 1 arcsec and 12
percent of the time better than 0.75 arcsec.

---------------------------------------------------------
Title: Eleven years of IRIS frequencies and splittings
Authors: Fossat, E.; Salabert, David; Cacciani, A.; Ehgamberdiev,
S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.;
Palle, P.; Schmider, F. X.; Tomczyk, S.
2003ESASP.517..139F Altcode: 2003soho...12..139F
Having acquired since July, 1989, a complete 11-year solar cycle of
full disk data, the IRIS++ network has now made available to anyone the
longest helioseismic data base to-date. A few results obtained from this
very long time series are briefly presented here, with some emphasis
on the low degree p-mode frequencies themselves, and their rotational
splittings that have been estimated with unprecedented accuracy.

---------------------------------------------------------
Title: A two color pupil imaging method to detect stellar oscillations
Authors: Cacciani, A.; Dolci, M.; Jefferies, S. M.; Finsterle, W.;
Fossat, E.; Sigismondi, C.; Cesario, L.; Bertello, L.; Varadi, F.
2003MSAIS...2..172C Altcode:
Observations of stellar intensity oscillations from the ground are
strongly affected by intensity fluctuations caused by the atmosphere
(scintillation). However, by using a differential observational method
that images the pupil of the telescope in two colors at the same
time on a single CCD, we can partially compensate for this source of
atmospheric noise (which is color dependant) as well as other problems,
such as guiding and saturation. Moreover, by placing instruments at
different locations (eg. Dome C and South Pole) we can further reduce
the atmospheric noise contribution by using cross-spectral methods,
such as Random Lag Singular Cross-Spectrum Analysis (RLSCA). (We
also decrease the likelihood of gaps in the data string due to
bad weather). The RLSCA method is well suited for extracting common
oscillatory components from two or more observations, including their
relative phases. We have evaluated the performance of our method
using real data from SOHO. We find that our differential algorithm can
recover the absolute amplitudes of the solar intensity oscillations
with an efficiency of 70%. We are currently carrying out tests using a
number of telescopes, including Big Bear, Mt. Wilson, Teramo and Milano,
while waiting for the South Pole and Dome C sites to become available.

---------------------------------------------------------
Title: The Scientific outlook for Astronomy and Astrophysics Research
at the CONCORDIA Station
Authors: Fossat, Eric; Candidi, Maurizio
2003MSAIS...2....3F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Visible Astronomy as well ? Why not !
Authors: Fossat, Eric
2003MSAIS...2..139F Altcode:
It is quite clear that the dry and cold astronomical site of dome
C has to be one of the best places on Earth, if not THE best, for
infrared and sub millimetric astronomical observations. In comparison
with usual observatories located in more usual latitudes, the benefit
to be expected in the visible range is a little less obvious. But
this benefit does exist indeed. The very long days and nights of the
Antarctic plateau provide a unique opportunity for extremely long
and nearly uninterrupted observations. Added to the expected reduced
amplitude of the stellar scintillation, this makes possible to consider
the feasibility of asteroseismic observations that were envisioned
only in space so far. Such night time astronomical programmes can be
developed very quickly, with moderately sized telescopes, and will
benefit of the first winter-over seasons at Concordia. When thinking
beyond the first few winters, the unique seeing properties of the
site look extremely promising for the combination of interferometry,
high performance adaptative optics and stellar coronography, or very
high contrast imaging, so that the direct observations of exoplanets
must be considered as a possibility for future observations on this
site. I briefly review here the first projects and ideas in these
directions. As many of these ideas are presented during this "visible"
session, you will find details, regarding most of them, in other papers
of these proceedings.

---------------------------------------------------------
Title: KEOPS: Kiloparsec Explorer for Optical Planet Search
Authors: Vakili, F.; Aristidi, E.; Fossat, E.; Abe, L.; Domiciano,
A.; Belu, A.; Agabi, A.; Schmider, F. X.; Lopez, B.; Swain, M.
2003sf2a.conf..365V Altcode: 2003sf2a.confE.165V
We present our proposal to develop an imaging optical interferometer at
Dome C of Antarctica optimized for both extra-solar planets detection
in the thermal infrared and direct astroseismology of nearby stars. The
science rationale as well as different steps of technological R&amp;D
to make this proposal successful against the adverse conditions of
polar nights will be described.

---------------------------------------------------------
Title: The Antarctic Planet Interferometer and the Potential for
Interferometric Observations of Extrasolar Planets from Dome C
Antarctica
Authors: Swain, M. R.; Coudé du Foresto, V.; Fossat, E.; Vakili, F.
2003MSAIS...2..207S Altcode:
We present a concept for studying exoplanets using an infrared
interferometer with a focused instrument design at the best accessible
site on Earth.

---------------------------------------------------------
Title: First daytime seeing monitoring at Dome C
Authors: Aristidi, E.; Agabi, A.; Vernin, J.; Azouit, M.; Martin,
F.; Ziad, A.; Fossat, E.
2003MSAIS...2..146A Altcode:
The first astronomical seeing monitoring has been made with a DIMM
instrument at the Antarctic plateau site of Dome C in December, 2002
on the bright star Canopus (alpha Eri) during the daytime. In these
far from optimal conditions, a median seeing of 1.2 arcsec as been
obtained, with extended periods better than 1 arc-sec and 12 percent
of the time better tan 0.75 arcsec.

---------------------------------------------------------
Title: SYMPA: A Dedicated Instrument and a Network for Seismology
of Giant Planets
Authors: Schmider, F. -X.; Gay, J.; Jacob, C.; Fossat, E.; Valtier,
J. -C.; Mosser, B.; Mekarnia, D.; Guillot, T.; Provost, J.
2003aahd.conf..449S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar p-modes from 1979 days of the GOLF experiment
Authors: Gelly, B.; Lazrek, M.; Grec, G.; Ayad, A.; Schmider, F. X.;
Renaud, C.; Salabert, D.; Fossat, E.
2002A&A...394..285G Altcode:
With the GOLF instrument onboard the SoHO observatory, 1979 days of
full-disc Doppler velocity observations have been compiled into a
study of p-mode properties. We develop a multi-step iterative method
(MSIM) algorithm to access all p-mode parameters while minimizing
any perturbating effect or cross-talk between parameters during their
determination. We present frequency and splitting tables, amplitudes,
linewidths, line asymmetries, pseudo-modes, and background noise
determinations. We have a first look at the changes induced by the
transition from the low-activity to the high-activity part of solar
cycle 23: we have recorded frequency shifts with a downturn at 3.7
mHz followed by a possible higher upturn, and linewidth changes to a
good accuracy. We detect an effect on the noise background at 3 mHz
possibly related to an interaction between noise and the modes and
connected to the asymmetry of the profiles.

---------------------------------------------------------
Title: IRIS++ database: Merging of IRIS + Mark-1 + LOWL
Authors: Salabert, D.; Fossat, E.; Gelly, B.; Tomczyk, S.; Pallé, P.;
Jiménez-Reyes, S. J.; Cacciani, A.; Corbard, T.; Ehgamberdiev, S.;
Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.; Schmider, F. X.
2002A&A...390..717S Altcode:
The IRIS network has been operated continuously since July 1st
1989. To date, it has acquired more than a complete solar cycle
of full-disk helioseismic data which has been used to constrain
the structure and rotation of the deep solar interior. However,
the duty cycle of the network data has never reached initial
expectations. To improve this situation, several cooperations have
been developed with teams collecting observations with similar
instruments. This paper demonstrates that we are able to merge data
from these different instruments in a consistent manner resulting
in a very significant improvement in network duty cycle over more
than one solar cycle initiating what we call the IRIS++
network. The integrated radial velocities from the IRIS++
database (1989 to 1999) are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/390/717

---------------------------------------------------------
Title: The concordia station in Antarctica: a real bargain for
astronomy?
Authors: Fossat, E.
2002sf2a.conf..453F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Variability of p-mode parameters in 11 years of
IRIS++ data
Authors: Salabert, D.; Jiménez-Reyes, S. J.; Fossat, E.; Gelly, B.;
Schmider, F. X.
2002ESASP.508...95S Altcode: 2002soho...11...95S
IRIS++ data (the low degrees l &lt;= 3 helioseismologic
network) have been analysed for the study of p-modes parameters
variability over the solar cycle 22 and the rising phase of cycle
23. This paper discusses the variations of all p-modes parameters along
these 11 years. We present the analysis of frequency dependance and time
dependance of p-modes frequencies and linewidths. We focus our attention
on frequency shifts and their evolution with solar acitivity. We also
study the different behaviours between modes of different degrees, and
the relation with solar activity indexes. We also discuss periodicities
shorter than 1 year which appear in the frequency shifts measurements.

---------------------------------------------------------
Title: p-mode frequencies variability in 15 years of IRIS++ data
Authors: Salabert, D.; Jimenez-Reyes, S.; Fossat, E.
2002sf2a.conf..565S Altcode:
IRIS++ data (the low degree l &gt;= 3 helioseismology network) have
been analysed for the study of p-modes parameters over the solar
cycle 22 and the rising phase of cycle 23. This paper discusses the
variations of all p-modes parameters along these 11 years. We present
the analysis of frequency dependance and time dependance of p-modes
frequencies and linewidths. We focus our attention on frequency shifts
and study their different behaviours between even and odd modes. We
discuss also about periodicities less than 1 year which appear in the
frequency measurements.

---------------------------------------------------------
Title: SYMPA: A Specified Instrument and a Dedicated Network for
Giant Planets' Sismology
Authors: Schmider, F. X.; Gay, Jean; Jacob, Cedric; Fossat, Eric;
Valtier, Jean-Claude; Mossier, Benoît; Mekarnia, Djamel; Guillot,
Tristan; Provost, Janine
2002sf2a.conf..611S Altcode:
The poster I will propose is about the 'SYMPA' project, an instrument
dedicated to the study of giant planets interiors, in paricular Jupiter,
based on principles of asterosismology. This instrument, developped in
collaboration between the department Fresnel of the Observatoire de la
Cote d'Azur, and the Laboratoire d'Astrophysique of Nice University,
is a Mach-Zender interferometer allowing observations of radial
velocities on jovien surface. The poster presents the contribution of
sismology to knowledge of planetary interiors, the principle of this
new imaging instrument and its performances, and some results from
first observations in february and march 2002.

---------------------------------------------------------
Title: 11 years of IRIS network exploitation
Authors: Fossat, E.; IRIS Group
2002sf2a.conf..521F Altcode:
IRIS, network of 6 stations of integrated sun heliosismic measures,
began in 1989 and thus acquired a complete solar cycle of 11 years at
the dawn of the 3rd millenium. Being never able to approach enough the
crucial rate of 100% coverage, IRIS developed co-operations to exploit
other complementary data, and became IRIS++. Having also developed
an original method of partial covering of the gaps in the data, which
exploits the characteristics of the signal in the Fourier space, the
data base IRIS++ reaches finally rates of annual coverage of about
80 to 90%, at the price of some acrobatic treatments which received
satisfactory solutions. The average frequencies and splittings of
rotation obtained with these 11 years of data can shamelessly be
compared with those of space instruments; the rotation, very fine
measure which improves with integration time being even better measured
by IRIS. If the other parameters of the p modes are less precisely
measured by IRIS and if the g modes are inaccessible to it without
real hope, alone the frequencies and splittings of the p modes largely
justify the investment.

---------------------------------------------------------
Title: Special Session: the future of astronomy at the dome C
concordia station in antarctica
Authors: Fossat, E.
2002sf2a.conf..449F Altcode:
The franco-italian station Concordia will be operational in 2004,
and 15 persons could spend winter there. The qualification of the
astronomical site and the first observations in infrared imagery and
visible photometry are scheduled for the first winters. The potential
of this site appears so promising that we must not ignore antarctica
in the european large projects propective debate. I will review what
is already known, and what we are going to measure to be certain,
and speak about collaborations that are being established.

---------------------------------------------------------
Title: Diurnal Atmospheric Extinction Over Oukaïmeden Observatory
using IRIS Database: 1989 1997. Comparison With The Other IRIS Sites
Authors: Siher, E. A.; Benkhaldoun, Z.; Fossat, E.
2002ExA....13..159S Altcode:
In this work, we use data of nine years (1989 to 1997) at allIRIS
sites (Culgoora, Kumbel, Oukaïmeden, Izaña, La Silla andStanford,
devoted to the study of the solar velocityoscillation) to study of
diurnal atmospheric extinctioncoefficient behaviour at Oukaïmeden
observatory and to compareit to the others. By this study, we
can conclude that the meanextinction coefficient at Oukaimeden
is around 0.120 magairmass-1. Besides, we show that
the daily extinctioncoefficient varies under the influence of the
seasonal effect.By the comparison of Oukaïmeden to the other sites, we
showedthat Oukaïmeden has a good photometric sky quality andconstitutes
a potential site for astronomical observations inthe north hemisphere.

---------------------------------------------------------
Title: Analysis of variability of p-mode parameters in 11 years of
IRIS data
Authors: Salabert, D.; Jiménez-Reyes, S. J.; Fossat, E.; Cacciani,
A.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov,
S.; Lazrek, M.; Pallé, P.; Schmider, F. X.; Tomczyk, S.
2002ESASP.477..253S Altcode: 2002scsw.conf..253S
11 years of IRIS (the low degree helioseismology network) have been
analysed for the study of p-modes parameters variability. The duty
cycle of the network data has been improved by the partial gap filling
method named "repetitive music". This paper discusses the variations
of all p-modes parameters along these 11 years.

---------------------------------------------------------
Title: The Concordia Antarctic Station: an opportunity for
asteroseismology and planetary search
Authors: Schmider, F. X.; Fossat, E.; Vernin, J.; Martin, F.; Azouit,
M.; Agabi, K.; Clausse, J. M.; Grec, G.
2002ESASP.485..219S Altcode: 2002sshp.conf..219S
Interruption in the obervations is a main limitation for
asteroseismology. It conducted to the development of networks and
spacecraft for asteroseismology as for helioseismology. However, the
continuity offered by polar locations has played an historical role
in the development of helioseismology, allowing the first measurement
of individual mode frequencies (Fossat et al. 1981). Several projects
were in the past envisioned for the exploitation of this capability for
stellar observations, but none of them were actually developed. From
2004, the permanent Antarctic station Concordia, will be running for
its first winter season. Located at Dome C, the Franco-Italian station
will hold several scientific programs, including glaciology, geophysics,
meteorology and astronomy. Continuity of the observations is not the
only advantage of the polar station for astronomy. The high altitude,
the low temperature and the incredible dryness of the site make it very
favorable for sub-mm and far IR observations. The Nice University has
already started the qualification of the site in the visible domain. Up
to now, no night data has been recorded yet about sky transparency
and seeing. However, they are good reasons to expect exceptional
conditions. In comparison with South Pole site, the location on a
dome provides very quiet weather with almost no wind. In consequence,
the seeing, mainly dominated at South Pole by ground layer, should
be excellent. Moreover, the absence of high altitude jet-stream let
expect a scintillation much lower than in any other place. This would
allow CCD observations to detect very faint photometric variations as
expected for asteroseismology, or planetary detection.

---------------------------------------------------------
Title: Spectral analysis of solar diameter measurements recorded at
Calern Observatory astrolabe during two solar cycles
Authors: Moussaoui, R.; Irbah, A.; Fossat, E.; Borgnino, J.; Laclare,
F.; Delmas, C.; Schmider, F. X.
2001A&A...374.1100M Altcode:
Solar diameter measurements performed with the Calern Observatory
astrolabe (O.C.A - France) during more than two solar cycles show
temporal variations. Due to the weather, seasonal effects and
instrumental characteristics, recorded solar data are non uniformly
sampled and present temporal gaps. Thus, to analyze these data,
diameter measurements averaged over one or more months have generally
been considered. This limits the accessible harmonic terms to a
low frequency range. To determine short-term periodicities from the
observed variations, all daily solar data need to be considered and
also corrected from the zenithal distance. In the present work, we use
two methods to analyze solar diameter measurements recorded at Calern
Observatory astrolabe during the observation period 1975-1996. They are
based on least square fits and deconvolution of the observation window
function. Results deduced from the analysis confirm harmonic terms
already found by other authors but also reveal new higher frequencies.

---------------------------------------------------------
Title: An estimation of global solar p-mode frequencies from IRIS
network data: 1989-1996
Authors: Serebryanskiy, A.; Ehgamberdiev, Sh.; Kholikov, Sh.; Fossat,
E.; Gelly, B.; Schmider, F. X.; Grec, G.; Cacciani, A.; Palle, P. L.;
Lazrek, M.; Hoeksema, J. T.
2001NewA....6..189S Altcode:
The IRIS network has accumulated full disk helioseismological data
since July 1989, i.e. a complete 11-year solar cycle. Since the
last paper publishing a frequency list [A&amp;A 317 (1997) L71],
not only has the network acquired new data, but has also developed
new co-operative programs with compatible instruments [Abstr. SOHO
6/GONG 98 Workshop (1998) 51], so that merging IRIS files with these
co-operative program data sets has made possible the improvement
of the overall duty cycle. This paper presents new estimations of
low degree p-mode frequencies obtained from this IRIS++
data bank covering the period 1989-1996, as well as the variation of
their main parameters along the total range of magnetic activity, from
before the last maximum to the very minimum. A preliminary estimation
of the peak profile asymmetries is also included.

---------------------------------------------------------
Title: GOLF data analysis using a whole spectrum fitting method:
temporal variations in 1445 days of the GOLF velocity signal
Authors: Lazrek, M.; Gelly, B.; Grec, G.; Renaud, C.; Fossat, E.;
GOLF Team
2001ESASP.464..523L Altcode: 2001soho...10..523L
The analysis of 1445 days of GOLF signal provides a first quick-look
to the solar cycle effects on the low order low-degree modes detected
by this instrument.

---------------------------------------------------------
Title: An Estimation of Global p-mode Frequencies and Splitting from
the IRIS Network Data: 1989-1996
Authors: Ehgamberdiev, Sh. A.; Serebryanskiy, A. V.; Khalikov, Sh. S.;
Fossat, E.; Gelly, B.; Teem, Iris
2001IAUS..203...97E Altcode:
The IRIS network has accumulated low-l modes data since July, 1989,
i.e. one complete solar cycle. Since the last publication of a frequency
table (in 1997) the IRIS data bank was not only filled with new data,
but also has been supplemented with data from other helioseismology
instruments, through cooperative programs. The results of a new
estimations of frequencies and splitting obtained with the resulting
increase of the global duty cycle, as well as their variation along
the solar magnetic activity cycle will be presented.

---------------------------------------------------------
Title: Analysis of Diameter Measurements Performed at Calern
Observatory Astrolabe
Authors: Moussaoui, R.; Irbah, A.; Abdelatif, T.; Fossat, E.; Borgnino,
J.; Laclare, F.; Delmas, C.
2000SoPh..195..433M Altcode:
Solar diameter measurements performed at Calern Observatory astrolabe
during more than two solar cycles show variations at various time
scales in a broad range. Due to seasonal effects and instrumental
characteristics, the recorded data are not sampled uniformly and
present some gaps during these years. This time series has been
analyzed by means of a deconvolution of the window function, as an
alternative method to the standard least square fits of harmonic
functions. The results show an extremely important improvement of
the power spectrum. Harmonic terms already found by other authors are
confirmed but new frequencies are also revealed by this analysis.

---------------------------------------------------------
Title: Full disk helioseismology: repetitive music and the question
of gap filling
Authors: Fossat, E.; Kholikov, Sh.; Gelly, B.; Schmider, F. X.;
Fierry-Fraillon, D.; Grec, G.; Palle, P.; Cacciani, A.; Ehgamberdiev,
S.; Hoeksema, J. T.; Lazrek, M.
1999A&A...343..608F Altcode:
Helioseismology requires continuous measurements of very long
duration, months to years. This paper addresses the specific and
limited case of full disk measurements of p-mode oscillations,
although it can be generalized, to some extent, to the case of imaged
helioseismology. First, a method of mode by mode (or rather pair of
modes by pair of modes) interpolation of the signal in gaps is tested,
and shown to be efficient for gaps as long as two days, but limited to
the frequency range where the signal to noise ratio is good. It is then
noted that the autocorrelation function of the full disk signal, after
dropping quickly to zero in 20 or 30 minutes, shows secondary quasi
periodic bumps, due to the quasi-periodicity of the peak distribution
in the Fourier spectrum. The first of these bumps, at 4 hours or so,
is higher than 70 percent and climbs to nearly 90 percent in limited
frequency ranges. This suggests that an easy gap filling method can
be developed, with a confidence of nearly 90 percent across all the
frequency range, as long as the gap does not exceed 8 hours, with
at least 4 hours of data at both ends. Even a short gap of one or
two periods is better filled by the data taken 4 hours earlier or
later than by local interpolation. This relaxes quite considerably
the requirement of continuity of the observations for the case the
full disk p-mode helioseismology. Applied to 7 years of IRIS data,
this method permits the detection of all low frequency p-modes already
seen by 2 years of the GOLF instrument data, and makes possible the
measurement of their frequencies with an accuracy consistent with the
partially filled 7 years of statistics.

---------------------------------------------------------
Title: On the Capability of Ground Based Networks to Precisely
Estimate the Solar Background in Full Disk Helioseismology
Authors: Fossat, E.; Kholikov, Sh.; IRIS Team
1999ASPC..173..309F Altcode: 1999sstt.conf..309F
No abstract at ADS

---------------------------------------------------------
Title: Power spectrum modelisation of helioseismic data: an
application to the measurement of solar p-mode uncertainties
Authors: Fierry Fraillon, D.; Gelly, B.; Schmider, F. X.; Hill, F.;
Fossat, E.; Pantel, A.
1998A&A...333..362F Altcode:
We estimate the statistical uncertainties of low-l solar p-modes
parameters based on a Monte Carlo approach. Random perturbations of
ideal Lorentz profiles L(a nu _i) can provide many estimations of the
set of p-modes parameters a and allow one to estimate statistical
error-bars sigma_ {a} by modelling the parameters' distribution
function. Unlike frequencies, which show symmetric distributions,
amplitudes and linewidths have asymmetric probability density function
similar to the distribution function for time-averaged energies of
stochastically excited solar p-modes (Kumar, 1988). A comparison between
sigma_ ν and uncertainties based on Hessian's computation (Libbrecht
1992, Toutain and Appourchaux 1994) shows a nice agreement. However,
our error-bars take into account more statistical effects, and rely
less on the initial parameters' estimation. Such a technique has
been used on the IRIS power spectra computed from gapped data, and
on one GONG power spectrum computed from almost continuous data. We
also present IRIS linewidths and error bars averaged over the years
1989-92 and computed with a fitting strategy using imposed frequency
which improves the value of both the parameter and its uncertainty.

---------------------------------------------------------
Title: Cross-Correlation Technique in Individual Splitting
Determination
Authors: Fierry Fraillon, D.; Lazrek, M.; Fossat, E.; Gelly, B.;
Golf Team
1998ESASP.418..161F Altcode: 1998soho....6..161F
We review here the cross-correlation technique applied to the individual
splitting measurement in Golf data. We perform the cross-correlation
of the same multiplet taken from two different power spectra: in the
ideal situation, the result is looking like a triplet of Lorentzian
for l = 1 (5 for l = 2 and 7 for l = 3) with a constant separation
given by the splitting (Lazrek et al. 1996). We use a continuous time
serie of 18-months Golf data, whith no frequency shift due to the
solar cycle (Fierry Fraillon et al. 1998), and we can then produce
6 differents realisations of the same multiplet corresponding to a
3-months spectral resolution. A sidereal value of the splitting is then
deduced for each n,l modes using the average of the corresponding 15
cross-correlations. The results show the independence of the splitting
as a function of the order n, and the agreement with a rigid solar
core rotation.

---------------------------------------------------------
Title: First Results on it P Modes from GOLF Experiment
Authors: Lazrek, M.; Baudin, F.; Bertello, L.; Boumier, P.; Charra,
J.; Fierry-Fraillon, D.; Fossat, E.; Gabriel, A. H.; García, R. A.;
Gelly, B.; Gouiffes, C.; Grec, G.; Pallé, P. L.; Pérez Hernández,
F.; Régulo, C.; Renaud, C.; Robillot, J. -M.; Roca Cortés, T.;
Turck-Chièze, S.; Ulrich, R. K.
1997SoPh..175..227L Altcode:
The GOLF experiment on the SOHO mission aims to study the internal
structure of the Sun by measuring the spectrum of global oscillations
in the frequency range 10-7 to 10-2 Hz. Here
we present the results of the analysis of the first 8 months of
data. Special emphasis is put into the frequency determination of the p
modes, as well as the splitting in the multiplets due to rotation. For
both, we show that the improvement in S/N level with respect to the
ground-based networks and other experiments is essential in achieving
a very low-degree frequency table with small errors ∼ 2 parts in
10-5). On the other hand, the splitting found seems to favour
a solar core which does not rotate slower than its surface. The line
widths do agree with theoretical expectations and other observations.

---------------------------------------------------------
Title: Performance and Early Results from the GOLF Instrument Flown
on the SOHO Mission
Authors: Gabriel, A. H.; Charra, J.; Grec, G.; Robillot, J. -M.;
Roca Cortés, T.; Turck-Chièze, S.; Ulrich, R.; Basu, S.; Baudin,
F.; Bertello, L.; Boumier, P.; Charra, M.; Christensen-Dalsgaard, J.;
Decaudin, M.; Dzitko, H.; Foglizzo, T.; Fossat, E.; García, R. A.;
Herreros, J. M.; Lazrek, M.; Pallé, P. L.; Pétrou, N.; Renaud, C.;
Régulo, C.
1997SoPh..175..207G Altcode:
GOLF in-flight commissioning and calibration was carried out during the
first four months, most of which represented the cruise phase of SOHO
towards its final L1 orbit. The initial performance of GOLF is shown
to be within the design specification, for the entire instrument as
well as for the separate sub-systems. Malfunctioning of the polarising
mechanisms after 3 to 4 months operation has led to the adoption of an
unplanned operating sequence in which these mechanisms are no longer
used. This mode, which measures only the blue wing of the solar sodium
lines, detracts little from the detection and frequency measurements of
global oscillations, but does make more difficult the absolute velocity
calibration, which is currently of the order of 20%. Data continuity
in the new mode is extremely high and the instrument is producing
exceptionally noise-free p-mode spectra. The data set is particularly
well suited to the study of effects due to the excitation mechanism
of the modes, leading to temporal variations in their amplitudes. The
g modes have not yet been detected in this limited data set. In the
present mode of operation, there are no indications of any degradation
which would limit the use of GOLF for up to 6 years or more.

---------------------------------------------------------
Title: Solar P-mode frequencies from the IRIS network.
Authors: Gelly, B.; Fierry-Fraillon, D.; Fossat, E.; Palle, P.;
Cacciani, A.; Ehgamberdiev, S.; Grec, G.; Hoeksema, J. T.; Khalikov,
S.; Lazrek, M.; Loudagh, S.; Pantel, A.; Regulo, C.; Schmider, F. X.
1997A&A...323..235G Altcode:
The Iris network for helioseismology has operated since 1989. We present
tables of solar p-mode frequencies for observations taken during the
four summer seasons from 1989 to 1992. This analysis uses the technique
of maximum likelihood fitting and a χ_2_^2^ model for the probability
density function of the spectrum. The simultaneous fitting of odd and
even pairs of peaks strengthens the identification of the l=3 eigenmodes
and improves the error bars on the 0-2 group. The frequencies are in
good agreement with other observational results and with theoretical
values for the D_0_ and the {DELTA}ν parameters of the asymptotic
approximation. A decrease of 0.25+/-0.12μHz is seen between the 1989
and the 1992 data sets. The change is associated with the decrease of
solar activity and is comparable with results of previous studies.

---------------------------------------------------------
Title: New IRIS constraints on the solar core rotation.
Authors: Gizon, L.; Fossat, E.; Lazrek, M.; Cacciani, A.; Ehgamberdiev,
S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov, S.; Palle, P. L.;
Pantel, A.; Regulo, C.; Schmider, F. -X.; Wilson, P. R.
1997A&A...317L..71G Altcode:
Four time series of IRIS data (4 to 6 months) have been used to obtain
improved measurements of the low degree (l=1,2,3) rotational splitting
frequencies. Assuming that the rotation law is known in the outer
layers of the Sun, we investigate the implications of IRIS splittings
for the central regions. Both a one-shell and a two-shell rotation
model have been considered in the solar core. A core rotating slightly
faster than the outer radiative envelope provides the best fit to the
data. Some evidence for the reliability of the observations is shown
by the visibility of differential rotation in the l=3 multiplets.

---------------------------------------------------------
Title: Performance and first results from the GOLF instrument on SoHO
Authors: Gabriel, A. H.; Charra, J.; Grec, G.; Robillot, J. -M.; Roca
Cortés, T.; Turck-Chièze, S.; Ulrich, R.; Baudin, F.; Bertello,
L.; Boumier, P.; Decaudin, M.; Dzitko, H.; Foglizzo, T.; Fossat, E.;
García, R. A.; Herreros, J. M.; Lazrek, M.; Pallé, P. L.; Pétrou,
N.; Renaud, C.; Régulo, C.
1997IAUS..181...53G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Three years of ANTENA: what we have done!
Authors: Belmonte, J. A.; Hernández, M. M.; Pérez Hernández, F.;
Vidal, I.; Roca Cortés, T.; Michel, E.; Auvergne, M.; Chevreton,
M.; Goupil, M. J.; Soufi, F.; Baglin, A.; Frandsen, S.; Viskum, M.;
Kjeldsen, H.; Christensen-Dalsgaard, J.; Schmider, F. X.; Fossat,
E.; Delache, Ph.; Provost, J.; Audard, N.; Berthomieu, G.; Paparó,
M.; Kovács, G.; Szabados, L.
1997IAUS..181..357B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Philippe Delache (8 October 1937 - 1994).
Authors: Fossat, E.
1997IAUS..181D..27F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: GOLF results: today's view on the solar modes
Authors: Grec, C.; Turck-Chièze, S.; Lazrek, M.; Roca Cortés, T.;
Bertello, L.; Baudin, F.; Boumier, P.; Charra, J.; Fierry-Fraillon,
D.; Fossat, E.; Gabriel, A. H.; Garcia, R. A.; Gelly, B.; Gouiffes,
C.; Régulo, C.; Renaud, C.; Robillot, J. M.; Ulrich, R. K.
1997IAUS..181...91G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Is the Solar Core Rotating Faster of Slower Than the Envelope?
Authors: Lazrek, M.; Pantel, A.; Fossat, E.; Gelly, B.; Schmider,
F. X.; Fierry-Fraillon, D.; Grec, G.; Loudagh, S.; Ehgamberdiev, S.;
Khamitov, I.; Hoeksema, J. T.; Pallé, P. L.; Régulo, C.
1996SoPh..166....1L Altcode:
The Sun is not a rigid body and it is well known that its surface
rotation is differential, the polar regions rotating substantially
slower than the equator. This differential rotation has been
demonstrated by helioseismology to continue down to the base of
the convective zone, below which it becomes closer to a rigid body
rotation. Far deeper, inside the energy generating core, the rotation
has generally been assumed to be much faster, keeping memory of the
presumably high speed of the young Sun. However, several recent results
of helioseismology have decreased this likelihood more and more,
so that the core rotation could be suspected to be only marginally,
or even not at all faster than the envelope. Certain results would
even imply a core rotation slower than the envelope, an interesting
but unlikely possibility. We present here a complete analysis of
the rotational splitting of the low degree modes measured in three
different time series obtained in 1990, 1991, and 1992 by the IRIS
full-disk network. With a time of integration slightly longer than 4
months, the splitting has been measured by 4 different global methods
on 42 doublets of l= 1, 35 triplets of l = 2, and 30 quadruplets of l =
3. With a high level of confidence, our result is consistent with a
rigid solar core rotation.

---------------------------------------------------------
Title: Global Oscillations at Low Frequency from the SOHO Mission
(GOLF)
Authors: Gabriel, A. H.; Grec, G.; Charra, J.; Robillot, J. -M.; Roca
Cortés, T.; Turck-Chièze, S.; Bocchia, R.; Boumier, P.; Cantin, M.;
Cespédes, E.; Cougrand, B.; Crétolle, J.; Damé, L.; Decaudin, M.;
Delache, P.; Denis, N.; Duc, R.; Dzitko, H.; Fossat, E.; Fourmond,
J. -J.; García, R. A.; Gough, D.; Grivel, C.; Herreros, J. M.;
Lagardère, H.; Moalic, J. -P.; Pallé, P. L.; Pétrou, N.; Sanchez,
M.; Ulrich, R.; van der Raay, H. B.
1995SoPh..162...61G Altcode:
The GOLF experiment on the SOHO mission aims to study the internal
structure of the sun by measuring the spectrum of global oscillations in
the frequency range 10−7 to 10−2 Hz. Bothp
andg mode oscillations will be investigated, with the emphasis on
the low order long period waves which penetrate the solar core. The
instrument employs an extension to space of the proven ground-based
technique for measuring the mean line-of-sight velocity of the viewed
solar surface. By avoiding the atmospheric disturbances experienced
from the ground, and choosing a non-eclipsing orbit, GOLF aims to
improve the instrumental sensitivity limit by an order of magnitude
to 1 mm s−1 over 20 days for frequencies higher than
2.10−4 Hz. A sodium vapour resonance cell is used in
a longitudinal magnetic field to sample the two wings of the solar
absorption line. The addition of a small modulating field component
enables the slope of the wings to be measured. This provides not only
an internal calibration of the instrument sensitivity, but also offers a
further possibility to recognise, and correct for, the solar background
signal produced by the effects of solar magnetically active regions. The
use of an additional rotating polariser enables measurement of the
mean solar line-of-sight magnetic field, as a secondary objective.

---------------------------------------------------------
Title: P-Mode Frequencies of Degree L = 3 TO 5
Authors: Pantel, A.; Hoeksema, T.; Fossat, E.; Scherrer, P.; Gelly,
B.; Grec, G.; Loudagh, S.; Schmider, F. X.
1995ESASP.376b.381P Altcode: 1995soho....2..381P; 1995help.confP.381P
No abstract at ADS

---------------------------------------------------------
Title: Solar Core Rotation: Latest IRIS Results
Authors: Fossat, E.; Lazrek, M.; Loudagh, S.; Pantel, A.; Gelly, B.;
Grec, G.; Schmider, F. X.; Pallé, P. L.; Régulo, C.; Ehgamberdiev,
S.; Khalikov, S.; Hoeksema, T.
1995ESASP.376b.261F Altcode: 1995help.confP.261F; 1995soho....2..261F
No abstract at ADS

---------------------------------------------------------
Title: Solar P-Mode Frequencies from the IRIS Network
Authors: Gelly, B.; Fossat, E.; Palle, P.; Appourchaux, T.;
Eghamberdiev, S.; Fierry-Fraillon, D.; Grec, G.; Hoeksema, J. T.;
Khalikov, S.; Lazrek, M.; Loudagh, S.; Pantel, A.; Regulo, C.; Sanchez,
L.; Schmider, F. X.
1995ESASP.376b.373G Altcode: 1995help.confP.373G; 1995soho....2..373G
No abstract at ADS

---------------------------------------------------------
Title: Philippe Delache, 1937 - 13 October 1994.
Authors: Barlier, F.; Bonnet, R. M.; Fossat, E.; Leibacher, J.;
Frisch, U.
1995JAF....47....2B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: IRIS Status Repport
Authors: Fossat, E.
1995ASPC...76....7F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: IRIS Data Merging and Deconvolution
Authors: Pantel, A.; Fossat, E.
1995ASPC...76..496P Altcode: 1995gong.conf..496P
No abstract at ADS

---------------------------------------------------------
Title: A New TEchnology Network for Asteroseismology - A.N.T.E.N.A.
Authors: Roca Cortes, T.; Belmonte, J. A.; Delache, P.; Michel, E.;
Frandsen, S.; Schmider, F. X.; Auvergne, M.; Fossat, E.; Vidal, I.;
Kjeldsen, H.; Douglas, N.; Lelievre, G.; Chevreton, M.; Vauclair,
G.; Audard, N.; Baglin, A.; Berthomieu, G.; Christensen-Dalsgaard,
J.; Dolez, N.; Goupil, M. J.; Perez Hernandez, F.; Pfeiffer, B.;
Provost, J.; Viskum, M.
1995ASPC...76..630R Altcode: 1995gong.conf..630R
No abstract at ADS

---------------------------------------------------------
Title: On the Solar Core Rotation - IRIS Results
Authors: Fossat, E.; Loudagh, S.; Gelly, B.; Grec, G.; Pantel, A.;
Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Khalikov, S.; Lazrek,
M.; Palle, P. L.; Regulo, C.
1995ASPC...76...24F Altcode: 1995gong.conf...24F
No abstract at ADS

---------------------------------------------------------
Title: On the Solar Core Rotation - IRIS Results
Authors: Fossat, E.; Loudagh, S.; Gelly, B.; Grec, G.; Panel, A.;
Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Khalikov, S.; Lazrek,
M.; Palle, P. L.; Regulo, C.
1995ASPC...76....4F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Working Group 20 - Low-degree p-mode Rotational Splittings
and Solar Core Rotations
Authors: Fossat, E.
1995ESASP.376a.229F Altcode: 1995heli.conf..229F
No abstract at ADS

---------------------------------------------------------
Title: IRIS Status Report
Authors: Fossat, E.
1995ASPC...76..387F Altcode: 1995gong.conf..387F
No abstract at ADS

---------------------------------------------------------
Title: Test of a Differential Photometer for Extinction Gradient
Correction in Full-Disk Helioseismology
Authors: Khatami, M.; Fossat, E.
1994ExA.....4..253K Altcode:
The ground based full disk velocity Doppler measurements used in
helioseismology suffer from an atmospheric noise component when the sky
transparency is not perfect. It is due to the non uniform integration
of the line of sight component of the solar rotation produced by the
differential atmospheric extinction across the direction of the solar
equator. A simple two-channel differential photometer is proposed for
measuring this differential extinction. The first laboratory tests
of this instrument show that it has the capability of performing
the required correction without adding a significant level of new
instrumental noise contribution.

---------------------------------------------------------
Title: On scintillation obfuscation
Authors: Badiali, M.; Catala, C.; Fossat, E.; Fransden, S.; Gough,
D. O.; Rocca-Cortes, T.; Schrijver, K.
1994Obs...114...53B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Oscillations: Full Disk Observations from the Geographic
South Pole
Authors: Grec, G.; Fossat, E.; Pomerantz, M.
1994snft.book..410G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Full-disk helioseismic IRIS raw data calibration.
Authors: Palle, P. L.; Fossat, E.; Regulo, C.; Loudagh, S.; Schmider,
F. X.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Khalikov, S.; Lazrek,
M.; Sanchez, L.
1993A&A...280..324P Altcode:
The International Research on the Interior of the Sun (IRIS)
helioseismometer measures the full disk line of sight velocity of the
Sun. In fact, it makes a photometric mesurement using two monochromatic
spectral windows located on the wings of the D1 solar line. This is
a non-linear measurement. Before a scientific exploitation of the
IRIS data, the instrumental signal must be converted from non-linear
photometric data into calibrated line of sight velocity. In this
process, it is necessary to extract the small component due to the
solar surface motions from the much larger contributions of the
Earth spin, the Earth orbit, the gravitational redshift, the D1
line distortions produced by solar activity and even some telluric
atmospheric effects. This paper describes the calibration method
which is now used for pre-processing the IRIS data. It is the result
of several iterations, and the use of one and a half years of IRIS
data from one instrument, at Teide Observatory. It is certainly the
best possible method to date, given the quality of the current data,
and it can be regarded as valid over all the entire p-mode frequency
range, and down to 100 microHz or so in the g-mode range. At lower
frequencies, calibration, solar noise and merging techniques cannot
be completely separated, and possible further improvements are still
under investigation.

---------------------------------------------------------
Title: Modeling of integrated sunlight velocity measurements: The
effect of surface darkening by magnetic fields
Authors: Ulrich, R. K.; Henney, C. J.; Schimpf, S.; Fossat, E.; Gelly,
B.; Grec, G.; Loudagh, S.; Schmider, F. -X.; Palle, P.; Regulo, C.
1993A&A...280..268U Altcode:
It has been known since the work by Claverie et al. (1982) that
integrated-sunlight velocities measured with the resonance scattering
technique show variations with time scales of weeks to months. The
cause can be understood in terms of the effects of solar activity
as was pointed out by Edmunds &amp; Gough (1983) and Andersen &amp;
Maltby (1983). The latter authors included a model calculation based on
sunspot areas which showed good promise of being able to quantitatively
reproduce the observed velocity shifts. We discuss in this paper a
new modeling effort based on daily magnetograms obtained at the 150-ft
tower on Mt. Wilson. This type of database is more quantitative than
sunspot area. Similar maps of magnetically sensitive quantities will
be measured on a continuous time base as part of several planned
helioseismology experiments (from space with the Solar Oscillations
Imagery/Michelson Doppler Imager (SOI/MDI) experiment on the Solar and
Heliospheric Observatory (SOHO), see Scherrer et al. (1991) or with
ground-based networks, see Hill &amp; Leibacher (1991)). We discuss
the correlations between various magnetically sensitive quantities and
develop a new model for the effects of magnetic field on line profiles
and surface brightness. From these correlations we integrate the
line profile changes over the solar surface using observed magnetic
field strengths measured at lambda 5250.2. The final output is a
new model for the effects of magnetic fields on integrated sunlight
velocities which we compare with daily offset velocities derived
from the International Research on the Interior of the Sun (IRIS)-T
instrument at the Observatorio del Teide.

---------------------------------------------------------
Title: The solar interior
Authors: Turck-Chièze, S.; Däppen, W.; Fossat, E.; Provost, J.;
Schatzman, E.; Vignaud, D.
1993PhR...230...57T Altcode:
This report confronts the different aspects of the solar interior from
the experimental and theoretical points of view, discussing photospheric
abundances, neutrinos and acoustic mode measurements. The theoretical
approach mainly concerns the classical framework of stellar evolution,
nevertheless, particle interpretation of the data and astrophysical
solutions invoked in the last 10 years are coherently examined.

---------------------------------------------------------
Title: A measurement of the I = I solar rotational splitting
Authors: Loudagh, S.; Provost, J.; Berthomieu, G.; Ehgamberdiev, S.;
Fossat, E.; Gelly, B.; Grec, G.; Khalikov, S.; Lazrek, M.; Palle,
P.; Regulo, C.; Sanchez, L.; Schmider, F. -X.
1993A&A...275L..25L Altcode:
A precise measurement of the l = 1 rotational splitting has been
derived from the 1991 IRIS data and it leads to a moderate rotation
rate in the solar core.

---------------------------------------------------------
Title: On Full Disk Helioseismology Power Spectra around the Cut-Off
Frequency
Authors: Regulo, C.; Fossat, E.; Roca-Cortes, T.; Ehgamberdiev, S.;
Gelly, B.; Grec, G.; Khalikov, S.; Lazrek, I. Khamitov M.; Palle,
P. L.; Sanchez-Duarte, L.
1993ASPC...42..103R Altcode: 1993gong.conf..103R
No abstract at ADS

---------------------------------------------------------
Title: On the acoustic cut-off frequency of the sun
Authors: Fossat, E.; Regulo, C.; Roca Cortes, T.; Ekhgamberdiev, S.;
Gelly, B.; Grec, G.; Khalikov, S.; Khamitov, I.; Lazrek, M.; Palle,
P. I.
1992A&A...266..532F Altcode:
Full solar disk observations of radial velocity, obtained with the IRIS
network of resonant scattering spectrometers, are used to analyze the
acoustic p-mode spectrum around the acoustic cut-off frequency. Three
different methods are used to determine it; two use the power spectrum,
while the third uses the phase spectrum. The three values measured
converge to a common value of 5.55 +/- 0.1 mHz, which is higher than any
theoretical prediction. Beyond this frequency, the power spectra still
decreases down to 10 mHz at which point it becomes flat, showing the
presence of some power due to the so-called pseudomodes which we show
are the result of interference between traveling waves. The acoustic
power density measured beyond the cut-off frequency makes it possible
to estimate the energy deposited into the chromosphere about 10 exp 7
erg/sq cm per sec, which is high enough to compensate the losses that
take place in this layer.

---------------------------------------------------------
Title: IRIS data merging. I. A solution to minimize the low and
intermediate frequency noise.
Authors: Fossat, E.
1992A&A...263..443F Altcode:
Time series of artificial low frequency noise have been produced to
simulate the instrumental and atmospheric noise in the full solar disk
measurements. They have been used to test various possible methods of
merging data obtained simultaneously at different sites with different
instruments operated under different sky conditions, with the goal of
minimizing the nonsolar noise level in the 0.02-1 mHz frequency range. A
merging method is proposed which implies a continuous window function
deconvolution and then a loss of information on the velocity signal
itself, but which proves to be far superior with respect to noise level.

---------------------------------------------------------
Title: Amplitude modulation of low-degree solar p-modes
Authors: Egamberdiev, S.; Khalikov, S.; Lazrek, M.; Fossat, E.
1992A&A...253..252E Altcode:
Due to the combined effect of varying interference between unresolved
individual p-modes and the true amplitude modulation of these p-modes,
the power spectrum obtained over one day of full-disk helioseismic
data varies strongly from day to day. The statistical distribution of
power within a given peak has accordingly been studied as a function
of modulation-amplitude magnitude. The result obtained is dependent on
the level of interdependence of the amplitude fluctuations displayed
by the various individual modes. Two independent, converging values
are obtained for the amplitude modulation.

---------------------------------------------------------
Title: Possible detection of Jovian global oscillations
Authors: Schmider, F. -X.; Fossat, E.; Mosser, B.
1991A&A...248..281S Altcode:
Observations of the Jupiter were carried out using a refined version of
the stellar seismometer with a sensitivity of better than 50 cm/s. The
observations revealed the existence of strong velocity variations of
the planets in the 10-20-min period range. It is concluded that the
observed variations can only be explained as global acoustic modes. The
frequencies of the modes are examined with reference to the internal
structure of the planet.

---------------------------------------------------------
Title: Global oscillation measurements at Kumbel station in frame
of the IRIS programme
Authors: Baijumanov, A.; Ehgamberdiev, Sh.; Fossat, E.; Grec, G.;
Ilyasov, S.; Kamaldinov, A.; Khalikov, Sh.; Khamitov, I.; Manigault,
J. F.; Menshikov, G.; Raubaev, S.; Yuldashbaev, T.
1991SoPh..133...51B Altcode:
The second of the IRIS network instruments was commissioned
in August 1988 at Kumbel mountain, located 75 km from Tashkent
(U.S.S.R.). Atmospheric and operating conditions on Kumbel are
discussed, as well as preliminary results derived from this station's
global solar oscillation measurements.

---------------------------------------------------------
Title: Preface
Authors: Fossat, Eric
1991SoPh..133D...7F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The IRIS sodium cell instrument
Authors: Grec, G.; Fossat, E.; Gelly, B.; Schmider, F. X.
1991SoPh..133...13G Altcode:
In the framework of the IRIS programme, full-disk solar Doppler-shift
measurements are made with an optical resonance sodium cell
spectrophotometer, a new pattern of the instrument successfully used
at the geographic South Pole 10 years ago. After many successive
improvements, the IRIS version has now become a precise and reliable
device, being limited only by the solar and/or by the atmospheric
noise in all the frequency ranges of interest for the p-mode and the
g-mode investigation. This instrument is described here in some detail,
with the technical specification for each individual component being
defined by comparison to the photon and the solar noise.

---------------------------------------------------------
Title: The IRIS Network for Full Disk Helioseismology - Present
Status of the Programme
Authors: Fossat, Eric
1991SoPh..133....1F Altcode:
IRIS (International Research on the Interior of the Sun) is the
name of a worldwide network of 8 observing stations for full disk
helioseismology. The IRIS scientific community is organizing a yearly
workshop in one of the 8 sites. This paper is the introduction to the
proceedings of the second IRIS workshop, held at Tashkent, Uzbekistan
SSR. It presents a brief history, the structure of the international
cooperation, the membership rule, the list of sites and members, the
scientific working teams additional structure and, as an appendix,
the report of the first meeting of the IRIS Scientific Committee.

---------------------------------------------------------
Title: General Presentation of a Single IRIS Site Raw Data Analysis
Problem
Authors: Egamberdiev, Sh.; Khalikov, S.; Fossat, Eric
1991SoPh..133...69E Altcode:
A complete software package has been built for the calibration in m s
−1 of the velocity residuals due to solar oscillations
in the raw IRIS (International Research on the Interior of the
Sun) data. It takes into account all known astronomical components
contributing to the line-of-sight velocity between the instrument
and the solar surface, and also the apparent velocity due to the
non-uniform integration of the solar rotation as seen through an
inhomogeneous Earth atmosphere. The IRIS data itself is used for the
estimation of the nonlinear instrumental response to the velocity,
and the residual can be directly obtained in velocity units, without
low frequency filtering. On a day of typical photometric sky quality,
the power spectrum obtained appears to be solar noise limited.

---------------------------------------------------------
Title: The Second IRIS Workshop. Proceedings. 2. IRIS (International
Research on the Interior of the Sun) Workshop, Tashkent, Uzbekistan
SSR (USSR), Sep 1989.
Authors: Egamberdiev, Sh.; Fossat, Eric
1991SoPh..133.....E Altcode:
Papers are presented on the IRIS (for International Research on the
Interior of the Sun program) sodium cell instrument, the IRIS data
management, global oscillation measurements at Kumbel Station in frame
of the IRIS program, the Moroccan participation in the study of solar
oscillations, and the general presentation of a single IRIS site raw
data analysis problem. Attention is given to some peculiarities of the
power spectrum of the 5-min solar brightness oscillations, new results
on the 160-min pulsation of the sun, 5-min variations of the global
magnetic field of the sun, the instrumental capabilities of the Sayan
Observatory for the study of oscillatory processes on the sun, and a
standard solar model of the asymptotic spectrum of gravity modes as a
function of the solar structures. Other papers are on solar convective
zone and acoustic oscillations and seismic probing of outer regions
of the sun.

---------------------------------------------------------
Title: Héliosismologie: observations.
Authors: Fossat, E.
1991sed..conf...23F Altcode:
Contents: (1) Introduction. (2) Les observables. (3) Les
observations. (4) Paramètres à mesurer. (5) Le problème du temps
d'intégration. (6) Les programmes d'observation actuels. (7) A propos
de la précision des mesures. (8) Sélection de quelques résultats
récents et de problèmes en suspens parmi d'autres. (9) En guise de
conclusion provisoire. (10) IRIS status report.

---------------------------------------------------------
Title: Jovian Seismology
Authors: Mosser, B.; Gautier, D.; Fossat, E.; Schmider, F. -X.;
Delache, Ph.; Gay, J.; Mekarnia, D.
1990BAAS...22.1065M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The IRIS network for full disk helioseismology. full disk
helioseismology. Present status of the programme
Authors: Schmider, Francois-Xavier; Fossat, Eric; Gelly, Bernard;
Grec, Gérard
1990LNP...367..241S Altcode: 1990psss.conf..241S
I.R.I.S.(International Research on the Interior of the Sun) is the
name of a worldwide network of 8 stations of observation in full disk
helioseismology. The I.R.I.S. scientific community is organizing a
yearly workshop in one of the 8 sites. This paper presents the status of
the network as it was for the second IRIS workshop, held at Tashkent,
Uzbekistan SSR, in September 1989. It presents a brief history, the
structure of the international cooperation, the membership rule, the
list of sites and members, the scientific working teams additional
structure and, as an appendix, the report of the first meeting

---------------------------------------------------------
Title: Full-disk Helioseismology in the Antarctic
Authors: Fossat, E.; Gelly, B.; Grec, G.; Schmider, F. -X.
1990AIPC..198..231F Altcode: 1989AIPC..198..231F; 1990asan.conf..231F
The South Pole has been an important site for unimaged helioseismology
since 1979. With the rapid development of helioseismology, observations
have evolved toward international network and space projects. Future
observations from the South Pole will have an important role
in validating data from low-latitude networks, obtained certain
measurements comparable only to those made in space and for imaged disk
data. The utility of the South Pole could be enhanced by combining
measurements ufrom the pole and at another Antarctic station such as
Dome C.

---------------------------------------------------------
Title: Seismological Study of Procyon and Arcturus
Authors: Schmider, F. X.; Fossat, E.
1989BCFHT..21...15S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Searching for solar g-modes, tests of a statistical method.
Authors: Fossat, Eric; Grec, Gerard; Gavrjusev, Vladimir; Gavrjuseva,
Elena
1988ESASP.286..393F Altcode: 1988ssls.rept..393F
The solar g-modes are extremely difficult to detect because of their
very small amplitude and because of the absence of any regular pattern
in their frequency distribution. A frequency dependent noise power
spectrum and a g-mode power spectrum can look extremely similar. The
authors propose to use crosscorrelation and autocorrelation methods to
test the presence of g-modes in a real power spectrum. This method is
used on 3 years of ACRIM irradiance data with negative conclusion. It
is also tested with synthetic g-modes computed into a standard and
a non standard model. Only the standard model seems to offer enough
regularity in rotational splitting and in period separation to make
reliable the measurement of these two parameters.

---------------------------------------------------------
Title: Effects of convective velocities on solar pressure mode
frequencies.
Authors: Delache, Philippe; Fossat, Eric
1988ESASP.286..671D Altcode: 1988ssls.rept..671D
There are persistent discrepancies between observations and
theoretical calculations of solar p-mode frequencies, νobs,
νcalc, in spite of improvements in the theory (e.g. equation
of state). In this short communication, the authors propose to
approximate roughly the difference (observation-calculation)
versus frequency as: δν = νobs-νcalc
≍ -Kν2, where the constant K is of the order of 1
second, and independent of degree l. It has been already suggested by
T. Brown that "Solar p-mode eigenfrequencies are decreased by turbulent
convection". The authors want to revisit this suggestion and reformulate
it in the following manner: is this physical effect responsible for
some of the difference ν0-νcalc? After a brief
discussion of the mechanism, the authors present an order of magnitude
evaluation which shows that, indeed, it is worthwhile to pursue the
idea further: this will be done in improving the description of the
coupling between convection and oscillations.

---------------------------------------------------------
Title: Solar calibration of asteroseismology.
Authors: Gelly, B.; Fossat, Eric; Grec, Gerard; Schmider, F. X.
1988ESASP.286..579G Altcode: 1988ssls.rept..579G
The first expected result of asteroseismology will consist in the
measurement of two parameters, Δν and D0, which in
the Tassoul's asymptotic approximation are close to the sound speed
integral across the solar radius, and to the sound speed gradient
inside the nuclear burning core, respectively. The first depends
mostly on the mass and evolves slowly with age, while the second is
strongly age dependant through the increase of molecular mass in the
stellar core. Theorists have started to built Δν - D0
diagrams, as a tool for the determination of mass and age of stars. For
a precise calibration of such a diagram the authors have made a precise
measurement of those parameters in the case of the sun.

---------------------------------------------------------
Title: Solar p-modes frequency variations between 1980 and 1986.
Authors: Gelly, B.; Fossat, Eric; Grec, Gerard
1988ESASP.286..275G Altcode: 1988ssls.rept..275G
Using a method of power spectra cross-correlation, the authors were
able in 1986 to confirm a 0.39 μHz decrease of solar low degree
p-mode frequencies between 1980 and the end of 1984. With the same
method applied to the 1984/85 South Pole data and to all the ACRIM
data obtained until april 1986, they again confirm the value of this
decrease. Moreover, they find an extreme stability of these frequencies
from spring 1984 to spring 1986 with a relative accuracy of 0.02 μHz.

---------------------------------------------------------
Title: The Nice University stellar seismometer.
Authors: Schmider, F. X.; Fossat, Eric; Grec, Gerard; Gelly, B.
1988ESASP.286..605S Altcode: 1988ssls.rept..605S
The authors' instrument devoted to stellar seismology uses a
Cacciani-type sodium cell as a very stable frequency reference for
radial velocity measurements. It was successfully operated for the
detection of oscillations on Procyon and Alpha Centauri in 1983 and
1984. In a new version, its sensitivity has been inreased and the
sources of noise have been reduced. The authors give a brief description
of the principle and discuss the limits of sensitivity. Other
possible applications are also suggested. Finally they discuss the
capabilities of this instrument in the context of the developement
of asteroseismology.

---------------------------------------------------------
Title: I.R.I.S.: a network for full disk helioseismology.
Authors: Fossat, Eric
1988ESASP.286..161F Altcode: 1988ssls.rept..161F
Presented in 1983 to the french "Institut National des Sciences de
l'Univers", the I.R.I.S. (for Installation d'un Réseau International
de Sismologie Solaire in french, or International Research on the
Interior of the Sun, in english) project was first funded in 1984 by
this Institute. It consists in the deployment of 7 observing stations
in full-disk helioseismology, distributed in complementary longitudes
and latitudes. This paper is a short presentation of the sites, teams,
and calendar of this network.

---------------------------------------------------------
Title: Modelling the solar oscillation time series by a randomly
excited oscillator.
Authors: Lazrek, Mohamed; Delache, Philippe; Fossat, Eric
1988ESASP.286..673L Altcode: 1988ssls.rept..673L
If the individual solar oscillations were pure standing waves of
constant amplitude inside a stationary Sun, there would be in principle
no intrinsic limits to the accuracy with which their frequencies could
be measured. Unfortunately, it is not so. In their analysis of 10
months of irradiance data from the SMM/ACRIM experiment, Woodard and
Hudson have proposed to describe the individual modes as independent
and chaotically excited oscillators, the linewidths being of the
order of 1.2 μHz in the central frequency range, around 3 mHz. This
paper deals with artificial full disk data. The goal is to determine
the parameters of a randomly excited oscillator by comparison with
the best data available. Such artificial signal is then used to test
the methods of analysis used for the precise determination of mode
frequencies, amplitudes and linewidths. The authors present tests of
the reliability of centroid measurements made by barycenter, Lorentzian
fit, Gaussian fit, with and without background noise. Several methods
are also tested for linewidth measurements.

---------------------------------------------------------
Title: GOLF: Global Oscillations at Low Frequencies for the SOHO
mission
Authors: Gabriel, A. H.; Bocchia, R.; Bonnet, R. M.; Cesarsky, C.;
Christensen-Dalsgaard, J.; Dame, L.; Delache, Ph.; Deubner, F. L.;
Foing, B.; Fossat, E.
1988sohi.rept...13G Altcode:
The GOLF (global oscillations at low frequencies) SOHO (solar
heliospheric observatory) mission is described. It aims to study
the internal structure of the Sun by measuring the spectrum of free
global oscillations. GOLF will measure both p and g mode oscillations,
with emphasis on low order long period waves which penetrate the
solar core. The instrument aims to measure frequencies between 10-7
and 6 10-3 Hz, with a sensitivity of 1 mm/s. The method involves an
extension to space of the ground based technique for measuring the mean
line-of-sight velocity of the solar surface. A sodium vapor resonance
scattering filter is used in a longitudinal magnetic field to sample the
two wings of the solar absorption line. The use of a modulating magnetic
field provides a continuous internal calibration of the sensitivity. By
adding an additional rotating polarizer, measurements are also made
of the average solar magnetic field. Efforts are made to correct the
data for the spurious effects caused by solar magnetic active regions.

---------------------------------------------------------
Title: Solar calibration of asteroseismology
Authors: Gelly, B.; Grec, G.; Schmider, F. -X.; Fossat, E.
1988A&A...200..207G Altcode:
The first expected result of asteroseismology will consist in the
measurement of two parameters, Δν and D0. The first depends
mostly on the mass and evolves slowly with age, while the second is
strongly age dependent through the increase of molecular mass in the
stellar core. Theorists have started to build Δν - D0
diagrammes, as a tool for the determination of mass and age of
stars. The authors have made a precise measurement of those parameters
in the case of the sun. D0 appears to be consistent, within
the here published error bar of 2%, with the frequency tables of the
most recent standard models. This is an extremely severe constraint
to be satisfied by every eventual non-standard model.

---------------------------------------------------------
Title: New analysis of the solar p-mode frequency change from 1980
to 1986
Authors: Gelly, B.; Fossat, E.; Grec, G.
1988A&A...200L..29G Altcode:
Using a method of power spectra cross-correlation, the authors were
able in 1986 to confirm a 0.39 μHz decrease of solar low degree
p-mode frequencies between 1980 and the end of 1984. With the same
method applied to their 1984/85 south pole data and to all Acrim data
obtained until April 1986, they again confirm this decrease, and on
the other hand, they find an extreme stability of these frequencies
from spring 1984 to spring 1986, with an accuracy of 0.02 μHz.

---------------------------------------------------------
Title: Evidence for Global Pressure Oscillations in Procyon and
Alpha-Centauri
Authors: Gelly, B.; Grec, G.; Fossat, E.
1988IAUS..123..249G Altcode:
For the full paper see Abstr. 42.116.003.

---------------------------------------------------------
Title: Seismology of the Stellar Cores
Authors: Fossat, E.
1988IAUS..132..209F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Helioseismology from the South Pole - the 1984/85 Campaign
Authors: Gelly, B.; Fossat, E.; Grec, G.; Pomerantz, M.
1988IAUS..123...21G Altcode:
More than 700 hours of full disk line of sight solar velocity have been
recorded at the Geographic South Pole between late November 1984 and
early February 1985. This paper presents very briefly some preliminary
results of the analysis of this data.

---------------------------------------------------------
Title: Sodium Cell Spectrophotometer for Detection of Stellar
Oscillations
Authors: Schmider, F. X.; Fossat, E.; Grec, G.; Gelly, B.
1988IAUS..123..513S Altcode:
This paper describes a new version of the authors' instrument used
for detection of stellar oscillations. It is planned to use it next
year for observations of Procyon and α Cen in order to confirm the
results already obtained.

---------------------------------------------------------
Title: Multi-year variations of solar oscillations
Authors: Fossat, Eric
1988AdSpR...8g.107F Altcode: 1988AdSpR...8..107F
Several solar oscillation time series exist now which are of enough
quality and duration for making possible an investigation of possible
long term variations of p-mode frequencies. The intrinsic accuracy on
the determination of an individual frequency is estimated by means
of the best available p-mode lifetime measurements. A statistical
estimation of the accessible amplitude of long term frequency drifts
is deduced. With an optimum integration time of the order of 6 months,
it is shown to be as small as 0.03 μ Hz. A critical review of results
published to-date in this investigation is then presented and discussed.

---------------------------------------------------------
Title: Search for Solar P-Mode Frequency Changes Between 1980 and 1985
Authors: Fossat, E.; Gelly, B.; Grec, G.; Pomerantz, M.
1987A&A...177L..47F Altcode:
704 hours of solar full disk velocity measurements obtained at the
South Pole between the end of November, 1984 and early February, 1985
have been analyzed. The p-mode power spectrum of this data and that
obtained in 1980 with the SMM / ACRIM instrument are compared by a
cross-correlation method. Taking into account the small bias in the
analysis due to the different window functions and to the different
relative responses to modes of degree 0 to 3, a frequency decrease of
0.39 μHz is found, with an uncertainty estimated at 0.04 μHz.

---------------------------------------------------------
Title: Evidence for global pressure oscillations in Procyon and
alpha Centauri.
Authors: Gelly, B.; Grec, G.; Fossat, E.
1986A&A...164..383G Altcode:
Helioseismology has proved to be a powerful tool to probe the
internal structure of the sun. With a new adapted optical-resonance
spectrophotometer, an extension has been attempted to two bright stars,
namely Alpha Cen A and Procyon. Results obtained from two observing
runs on Alpha Cen A in May 1983 and May 1984 at La Silla, and one
observing run on Procyon in February 1984 at Hawaii are presented. In
both cases, solarlike pressure oscillations have been detected. The
complete analysis determines essentially five parameters: the frequency
range, the amplitudes, the mean equidistance, the departure around this
equidistance (curvature of the echelle-diagram), and the fine frequency
spacing between modes of degree 0 and 2. For Procyon, all results
are consistent with theoretical predictions, including excitation
of oscillations, mass, radius, and age of the star. For Alpha Cen,
all the results are consistent together and are confirmed by the 1984
observations. They suggest that Alpha Cen A might be younger than
estimated, which is consistent with a ZAMS star.

---------------------------------------------------------
Title: Evidence for p-modes on Alpha Centauri and Procyon.
Authors: Fossat, E.; Gelly, B.; Grec, G.
1986ASIC..169..405F Altcode: 1986ssds.proc..405F
Helioseismology has proved to be a powerful tool to probe the
internal structure of the Sun. With a new adapted optical resonance
spectrophotometer, an extension has been attempted to Alpha Centauri
A and Procyon. In both cases, solar-like pressure oscillations have
been detected. The complete analysis is presented, which leads to
determine essentially five parameters: the mean equidistance Δν,
the frequency range, the amplitudes, the departure around equidistance
(curvature of the Echelle diagram) and the fine frequency spacing
between modes of degrees 0 and 2.

---------------------------------------------------------
Title: Global Oscillations
Authors: Fossat, E.
1985ESASP.235..209F Altcode: 1985fmsh.work..209F; 1985shpp.rept..209F
It is now possible to probe the solar models and the solar rotation over
more than 60% of the outer solar radius. Some significant disagreement
remains between observation and theory, and the author concentrates his
presentation on the discussion of the already obtained and expected
future benefits of full disk measurements in this quest for the best
possible fit.

---------------------------------------------------------
Title: Advances in Solar Seismology at the South Pole
Authors: Pomerantz, M. A.; Fossat, E.; Gelly, B.; Grec, C.; Harvey,
J. W.; Duvall, T. L.
1985AnJUS..20..221P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar observations at the South Pole.
Authors: Fossat, E.; Grec, G.
1985BCSAB..71..177F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atmospheric limitations in stellar seismology: Should one
measure radial velocity or brightness fluctuations?
Authors: Fossat, E.
1984NASCP2350...68F Altcode: 1984itp..work...68F
Low degree p-modes of the Sun have been measured in spatially
integrated sunlight (the Sun as a star) both in Doppler shift and
in intensity fluctuations. These observations are a good starting
point for the discussion of the best way to collect equivalent data
on other stars. It is assumed that the Sun is removed far enough in
space to become an ordinary star of magnitude zero to one. Evidently
another star will oscillate with different frequencies and different
amplitudes, but some reference must be made to start with. Using this
scheme, a detailed investigation of the limitations of observational
accuracy in the search for global p-modes is made. The sources of noise
stand in the Sun itself, in the instrumentation, in the observing
time duration, in the corpuscular nature of the light and mostly in
the Earth atmosphere in the case of ground based observations.

---------------------------------------------------------
Title: Five-minute P modes detected in Doppler shift measurement on
Alpha Centauri
Authors: Fossat, E.; Grec, G.; Gelly, B.
1984NASCP2350...28F Altcode: 1984itp..work...28F
A spectrophotometer using the principle of optical resonance
spectroscopy, designed for the goal of identifying radial and weakly
non radial eigenmodes in the five minute range in the case of stars,
is discussed. The conclusion of the first test of this new instrument
was that if the observation can be photon noise limited (i.e., in
total absence of any instrumental source of noise), the five-minute
solar oscillation could still be detected by removing the Sun far
enough for its magnitude to become zero or one. Such a situation
is very closely represented by the observation of Alpha Centauri A,
because it is a G2 V star, very similar to the Sun, with a mass of
1.1 in solar unit. Six nights were granted to this program on a 3.6m
telescope, from 22 to 28 May 1983. Two and half nights provided over
20 hours of data of photometric quality good enough for analysis.

---------------------------------------------------------
Title: Solar large scale velocity structures from optical resonance
method
Authors: Robillot, J. M.; Bocchia, R.; Fossat, E.; Grec, G.
1984A&A...137...43R Altcode:
Preliminary observations have been made to search for large
scale velocity fields by means of sodium optical resonance
spectrophotometry. The authors recall that the standard method measures
only 2 points of the line, in order to derive the Doppler shift. They
point out an ambiguity from line profile distortion, because apparent
upflows are seen in the wide area of active regions. In any case, this
can explain the long-term modulation observed in full disk Doppler
measurements (Claverie et al., 1982) without the need of invoking a
rapidly rotating core. In the quiet solar atmosphere, an upper limit
of 15 m s-1 rms for the large scale (≥50,000 km) velocity
distribution is deduced. A relatively simple optimization of the optical
resonance technique is suggested in order to progress in this field.

---------------------------------------------------------
Title: Detection des oscillations de pression sur alpha du Centaure.
Authors: Fossat, E.; Grec, G.; Gelly, B.; Decanini, Y.
1984CRASB.299...17F Altcode: 1984CR2...299...17F; 1984CRSPH.299...17F; 1984CRASM.299...17F
Optical resonance spectrophotometry was used to scan Alpha Centauri
(G2V) for evidence of oscillations. Data were taken over six nights in
May 1983 with a 3.6 m telescope. The results comprised the monochromatic
intensity in the red region of the Na D1 and D2 lines and the total
intensity at 20 A centered on the D lines. A Fourier transform analysis
of the data in terms of frequency and phase revealed a 5 min period
similar to that exhibited by the sun. The periodic structure appeared
between 3-3.5 MHz and had a period of 80 micro-Hz, and were close in
frequency and structure to solar p-modes. Implications of the discovery
for analysis of convective forces and the composition of the two stars
are discussed.

---------------------------------------------------------
Title: Stellar seismology - Five-minute P modes detected on Alpha
Centauri
Authors: Fossat, E.; Grec, G.; Gelly, B.; Decanini, Y.
1984Msngr..36...20F Altcode:
A spectrophotometer was devised for detecting seismic disturbances
in stellar sources. Based on the principle of optical resonance
spectroscopy, the instrument is capable of 1/msec oscillation amplitude
Doppler shift measurements. Twenty hours of data on Alpha Centauri
covered the monochromatic intensity in the red wings of Na D1 and
D2 lines and a 20 A passband of an interference prefilter used in
a reference channel. Steps were taken to account for atmospheric
interference and determine the harmonics using Fourier analysis. An
81.3 micro-Hz period was observed for a 2.3-3.8 mHz periodicity in the
power spectrum, a result that is similar to a period detected in the
Sun, thereby indicating that a 5 min p-mode may also be occurring in
Alpha Centauri.

---------------------------------------------------------
Title: Low degree p-modes observed in velocity and brightness Future
in the frame of the space-ground competition
Authors: Fossat, E.
1984MmSAI..55...47F Altcode:
Observational data on low-degree p-mode solar oscillations are
summarized, and observational techniques to provide further information
are discussed in detail. The specific advantages of full-disk,
center/outer-annulus, and two-dimensional-imaging observations are
indicated; the need for longer time series to determine the lifetimes
of amplitude and phase modes, their frequency variation, the fine
structure of individual power-spectrum peaks, and the nature of the
160-min oscillation is stressed; stellar p-modes are considered;
and the sources of noise in ground-based and spaceborne observations
(photon noise, telescope guiding, apparatus instability, scintillation,
and transparency changes) are examined. It is found that both solar and
stellar Doppler-signal observations are already photon-noise-limited
from the ground, but the quality of solar-brightness measurements and
broadband photometry of stars can be greatly improved from space.

---------------------------------------------------------
Title: Five-minute P Modes Detected in Doppler Shift Measurement on
Alpha Centauri
Authors: Fossat, E.; Gelly, B.; Grec, G.
1984LIACo..25..229F Altcode: 1984trss.conf..229F; 1984tpss.conf..229F
No abstract at ADS

---------------------------------------------------------
Title: Solar Oscillations (text not received)
Authors: Fossat, E.
1984faa..conf...69F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Should One Measure Radial Velocity or Brightness Fluctuations
Authors: Fossat, E.
1984srps.conf...77F Altcode:
Low degree p-modes of the sun have been measured in spatially integrated
sunlight both in Doppler shift and intensity fluctuations. The guideline
of this paper is to assume that the sun is removed far enough in space
to become an ordinary star of magnitude zero to one. Evidently, another
star will oscillate with different frequencies and different amplitudes,
but one must use some reference to start with. With this scheme, a
detailed investigation of the limitations of observational accuracy in
the search for global p-modes is made. The sources of noise stand in the
sun itself, in the instrumentation, in the observing time duration, in
the corpuscular nature of the light and mostly in the earth atmosphere
(for ground-based observations). Finally, a detection of five minute
p-modes on α Cen are reported.

---------------------------------------------------------
Title: First Test of the New Spectrophotometer Devoted to Stellar
Seismology
Authors: Fossat, E.; Decanini, Y.; Grec, G.
1983Msngr..33...29F Altcode:
Solar seismology (or helioseismology) was born in 1975. Since that
recent date it provided the first unambiguous information regarding
the internal structure of the sun.

---------------------------------------------------------
Title: Full-Disk Observations of Solar Oscillations from the
Geographic South-Pole - Latest Results
Authors: Grec, G.; Fossat, E.; Pomerantz, M. A.
1983SoPh...82...55G Altcode: 1983IAUCo..66...55G
This paper presents the latest results obtained from the analysis of
the full-disk Doppler shift observations obtained at the geographic
South Pole in 1981. About 80 normal modes of oscillation (l = 0-3)
have now been identified. Their frequencies range from 1886 μHz (l =
1, n = 12) to 5074.5 μHz (l = 2, n = 35), and their amplitudes are as
low as 2.5 cm s-1. Amplitude modulation occurs with periods
of 1-2 days, and the individual oscillations appear to be excited
randomly and independently. In cases where other groups have observed
some of the modes identified by us, the agreement in frequency is good.

---------------------------------------------------------
Title: A spectrophotometer devoted to stellar seismology.
Authors: Fossat, E.; Decanini, Y.; Grec, G.
1982ASSL...92..169F Altcode: 1982IAUCo..67..169F; 1982ialo.coll..169F
An overview of stellar seismology observation techniques is
given, stressing a new instrument developed in Italy. A solar
spectrophotometric method, requiring high sensitivity and high temporal
resolution, has identified 75 various modes of oscillation. This method
can be improved by performing more observations from the Antarctic
and from space, and it is also proposed that similar observations
of different stars may be useful in understanding the theory of
stellar evolution. A proposed technique for making such observations
uses optical resonance. A beam is transmitted through sodium vapor,
between two crossed linear polarizers. A Wollaston prism can be used to
replace the entrance polarizer, in order to utilize both directions of
polarization. It appears that the photon efficiency of this instrument
is comparable to other spectroscopic techniques, but it has the
advantage of the high spectral stability of the optical resonance.

---------------------------------------------------------
Title: Solar Pulsations Observed from the Geographic South Pole -
Initial Results
Authors: Fossat, E.; Grec, G.; Pomerantz, M.
1981SoPh...74...59F Altcode:
Initial results of round-the-clock observations of solar oscillations at
the South Pole are briefly summarized by describing the Figures 1 to 4.

---------------------------------------------------------
Title: Atomic Beam and Optical Resonance Cells
Authors: Fossat, E.; Grec, G.
1981siwn.conf..135F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Pulsations: Report from the Antarctic
Authors: Fossat, E.; Grec, G.; Pomerantz, M.
1981siwn.conf..385F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar and stellar oscillations.
Authors: Fossat, E.
1981ASIC...68...75F Altcode: 1981spss.conf...75F
An introduction is provided to the field of solar and stellar
seismology, which uses observations of global pulsations as probes of
the interior structures of the sun and stars. The nature of stellar
or solar oscillations is discussed, and the restoring forces and
excitation mechanisms involved in the establishment of the oscillations
are identified. Observational data needed to constrain theoretical
models of stellar and solar oscillations is indicated, and the primary
methods by which this information is obtained are presented, including
Doppler shift measurements, measurements of intensity fluctuations
and astrometry. Some of the most important results of solar seismology
are presented, including the resolution of the five-minute ridges, and
observations of solar diameter oscillations, radial and low-l modes in
the five-minute range, and long-period solar oscillations. Potentials
for the observation and identification of small-amplitude nonradial
oscillations on nonvariable stars other than the sun are also noted.

---------------------------------------------------------
Title: When the Sun vibrates.
Authors: Fossat, E.
1981Rech...12.1280F Altcode:
No abstract at ADS

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Title: Solar oscillations: full disk observations from the geographic
South Pole
Authors: Grec, G.; Fossat, E.; Pomerantz, M.
1980Natur.288..541G Altcode:
Observing conditions at the geographic South Pole enable modes of
global solar oscillations and theoretical models of the internal solar
structure to be identified.

---------------------------------------------------------
Title: Shaking Down the Sun's Long-Period Vibes
Authors: Kotov, V. A.; Severny, A. B.; Tsap, T. T.; Scherrer, P. H.;
Wilcox, J. M.; Fossat, E.; Grec, G.; Pomerantz, M.
1980SciN..118..100K Altcode:
No abstract at ADS

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Title: Solar Seismology: A New View from the South Pole
Authors: Pomerantz, M. A.; Grec, G.; Fossat, E.
1980AnJUS..15..200P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comment about phase coherence of solar diameter pulsations.
Authors: Grec, G.; Fossat, E.
1979MNRAS.188P..21G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar pulsations and angular coherence of atmospheric
transparency fluctuations.
Authors: Grec, G.; Brandt, P.; Fossat, E.; Duebner, F. L.
1979A&A....77..347G Altcode:
It is noted that radial-velocity measurements in integrated sunlight
are contaminated by atmospheric noise due to inhomogeneous transparency
of earth's atmosphere along the line of sight to the solar disk. A
measurement of the angular autocorrelation function of slow fluctuations
in atmospheric transparency is described. It is shown that the typical
coherence size is about 1 deg and independent of fluctuation amplitudes
of 0.7 percent to 30 percent and that the angular autocorrelation
function provides a link between global transparency variations and
spurious measured velocities. It is concluded that all ground-based
full-disk Doppler measurements should be carefully interpreted because
atmospheric noise is present for periods greater than 5 min and less
than about 90 min.

---------------------------------------------------------
Title: Calculation of pseudo narrow band oscillations produced by
atmospheric differential extinction.
Authors: Grec, G.; Fossat, E.
1979A&A....77..351G Altcode:
It is suggested that diurnal effects due to the atmospheric transparency
may give rise to systematic drift in solar Doppler measurements. The
effect of differential atmospheric transparency on measurements
is investigated. It is shown to favour harmonic 8, 9, and 10 for
measurement durations from 4 to 10 h. This effect can explain an
amplitude close to 1 m/s for these harmonics, and also the appearance
of phase coherence over long time periods.

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Title: The sun, a variable star.
Authors: Fossat, E.; Souffrin, P.
1978Rech....9..526F Altcode:
The paper describes supergranules in the solar surface and a local
oscillation with a 5-minute frequency in the solar atmosphere. The
supergranules can be approximately 30 times the size of the granules
and are more stable than the granules, the supergranules persisting
more than 10 hours, that is, more than 100 times the lifetime of a
granule. While the existence of two systems - granules and supergranules
- can not yet be explained by convection theory, the horizontal
movements in the supergranules do explain the reticular structure
of the solar magnetic field, as the movement from the center to the
edge of the supergranule drags the magnetic field to the border. The
local oscillations extend a distance of a few thousand meters and
persist approximately 20 minutes. The implications of supergranules
and local oscillation for an understanding of the external layers of
stars are discussed.

---------------------------------------------------------
Title: Experiments for large multi-mirror telescopes. I.- Detection
of non radial stellar oscillations.
Authors: Roddier, F.; Fossat, E.; Grec, G.; Roddier, C.
1978otf..conf..357R Altcode:
Preliminary measurements made with a 2-m telescope equipped with a
sodium cell have shown that nonradial oscillations similar to the
solar 5-min oscillations could be detected on bright stars with an
integration time of three hours and a 5-m telescope. Because of their
aberrations, large optical telescopes of the future will act as light
collectors rather than imaging devices. An analysis demonstrates how
interferometric techniques can be used to obtain good images with a
multi-mirror telescope.

---------------------------------------------------------
Title: Atmospheric Effects in Long Period Pulsation Studies
Authors: Fossat, E.; Grec, G.
1978pfsl.conf..151F Altcode: 1978ESPM....2..151F
No abstract at ADS

---------------------------------------------------------
Title: Photospheric oscillations. IV. An accurate omega -spectrum
at low values of k.
Authors: Fossat, E.; Grec, G.; Slaughter, C.
1977A&A....60..151F Altcode:
Two spatiotemporal (k - omega) power spectra of the solar five-minute
oscillation are calculated with a resolution of 0.3 mHz for an 8.5-ft
and a 36-in. aperture, respectively. The two spectra are found to
appear almost identical except in the low-frequency range, where
differences arise due to large amounts of atmospheric noise. An average
omega-spectrum is determined from the two power spectra and is compared
with a previously computed power spectrum. It is concluded that for
wavenumbers (k) not exceeding 0.0001 per km, the dependence of the
unresolved omega-spectrum on wavenumber is fairly weak and that the
average of the two spatiotemporal power spectra can be regarded as
a good estimate of the unresolved omega-spectrum for any wavenumber
bandwidth in the range from 0 to 0.0001 per km.

---------------------------------------------------------
Title: Apparent solar oscillations and fluctuations in the earth's
atmosphere.
Authors: Fossat, E.; Harvey, J.; Hausman, M.; Slaughter, C.
1977A&A....59..279F Altcode:
Measurements of air mass fluctuations are presented and interpreted with
a simple model. Such fluctuations can produce a spectrum of apparent
solar diameter fluctuations similar in magnitude with the spectrum of
observed apparent solar diameter fluctuations.

---------------------------------------------------------
Title: Photospheric Oscillations. III. Search for Long Period Modes
Authors: Grec, G.; Fossat, E.
1977A&A....55..411G Altcode:
Summary. The stability of the sodium optical resonance device has been
optimised for the study of long period solar pulsations. Observations
are made on the integrated solar light, which are insensitive to
guiding errors. The residual five-minute oscillation is clearly
observed with a r.m.s. amplitude of about 2 m s `. The low frequency
spectrum is carefully examined in the range of periods between five
minutes and 1.5 h, with a sensivity of 70 cm s `. After subtraction
of the slow drifts, the data are treated by standard Fourier analysis
and time correlations. It is shown that the power spectra never rise
above the statistical significance level. It is concluded that solar
oscillations, if they exist, must have an amplitude smaller than 70 cm
s - in integrated light. Key words: sun - photosphere oscillations -
long period modes

---------------------------------------------------------
Title: A spectrophotometer for the study of long period solar
photospheric oscillations.
Authors: Grec, G.; Fossat, E.; Vernin, J.
1976A&A....50..221G Altcode:
The paper describes a sodium optical resonance photoelectric
spectrophotometer for measuring the Doppler shifts of the Na D1 line
in the solar photosphere. The photometer operates on the basis of
absorption of the spectral windows corresponding to the sigma Zeeman
components. Problems of sensitivity (photon noise, guiding, residual
modulation due to clouds) are considered, and the optimization of the
spectrophotometer for the study of long period photospheric oscillations
is discussed. A sensitivity of 1 m/s is expected for a velocity field
integrated over the spectral range 0-1 MHz.

---------------------------------------------------------
Title: TECHNOLOGIE: Mechanicals deformation studies of astronomical
instrument using interferometric method
Authors: Ricort, G.; Aime, C.; Fossat, E.
1976NROpt...7...63R Altcode:
An interferometric method which permits the precise measurement of the
instantaneous mechanical deformation of a telescope as a function of
any parameter (weight, vibration, heating, etc.) is described. Two small
mirrors fixed at the telescope aperture are illuminated by a laser from
the focus of the instrument, and the resulting interference fringes
are observed microscopically. Mechanical deformation of the instrument
results in a motion of the fringes in the plane of observation. The
technique has been used to measure the flexure of the Nice Coude
telescope. The thermal stabilization time was found to be about
20 min. A continuous deformation as a function of the hour angle,
corresponding to fringe motion at about 1 arc sec/min, was observed.

---------------------------------------------------------
Title: Observations of the Line-Of-Sight Velocity
Authors: Fossat, E.
1976IAUTB..16..244F Altcode: 1976IAUT...16B.244F
No abstract at ADS

---------------------------------------------------------
Title: Photospheric oscillations. II - Acoustic filtering in the
solar atmosphere and heating of the chromosphere
Authors: Fossat, E.; Ricort, G.
1975A&A....43..253F Altcode:
Summary. Intensity fluctuations in the wings of the Fraunhofer line
Na D t 5896 have been recorded for about two hundred hours at the
focus of the Nice coude' refractor, using a sodium optical resonance
device. Because of the large beam aperture available, records have
been made on circular apertures from 22" up to 32' diameter (the whole
sun). The principal results from the analysis of these data are: -
As shown by White and Cha (t973), the five-minute oscillation has a
gaussian random character with a mean lifetime of about 20 min. Its
two-dimensional spatial power spectrum is roughly gaussian for every
temporal frequency between 2 and 6 MHz. The width of this gaussian
spectrum is near 5 t0- km -1 (i.e. 2 = 20000 km). It is shown that this
value corresponds to a cellular pattern having a "coherence scale"
near 5000 km. Various results published since 1962 concerning this
coherence scale become consistent by taking a unified definition of this
scale. - A new oscillatory mode of to min period has been discovered,
for photo spheric apertures larger than 3' It does not appear to have
the random gaussian character of the 5-min mode, but seems to be a
spasmodical phenomenon, both in space and time. Key words: optical
resonance photo spheric oscillations

---------------------------------------------------------
Title: Photospheric oscillations. I. Large scale observations by
optical resonance method.
Authors: Fossat, E.; Ricort, G.
1975A&A....43..243F Altcode:
Summary. Intensity fluctuations in the wings of the Fraunhofer line
Na D t 5896 have been recorded for about two hundred hours at the
focus of the Nice coude' refractor, using a sodium optical resonance
device. Because of the large beam aperture available, records have
been made on circular apertures from 22" up to 32' diameter (the whole
sun). The principal results from the analysis of these data are: -
As shown by White and Cha (t973), the five-minute oscillation has a
gaussian random character with a mean lifetime of about 20 min. Its
two-dimensional spatial power spectrum is roughly gaussian for every
temporal frequency between 2 and 6 MHz. The width of this gaussian
spectrum is near 5 t0- km -1 (i.e. 2 = 20000 km). It is shown that this
value corresponds to a cellular pattern having a "coherence scale"
near 5000 km. Various results published since 1962 concerning this
coherence scale become consistent by taking a unified definition of this
scale. - A new oscillatory mode of to min period has been discovered,
for photo spheric apertures larger than 3' It does not appear to have
the random gaussian character of the 5-min mode, but seems to be a
spasmodical phenomenon, both in space and time. Key words: optical
resonance photo spheric oscillations

---------------------------------------------------------
Title: Statistical analysis of a plate corrected for photographic
noise.
Authors: Ricort, G.; Aime, C.; Fossat, E.
1974A&A....37..105R Altcode:
The paper describes a statistical analysis method for the correction,
for photographic noise, of the spatial power spectrum of the density
fluctuations of a photospheric solar granulation plate. It is
assumed that the photographic noise is statistically independent
of the signal. If this noise is ignored, any spatial frequency
is overestimated. Increasing the size of the spot is inefficient,
because, although the photographic noise is reduced at the highest
frequencies, nothing is changed for all the lower frequencies of the
signal. Signal/noise discrimination can be made using the difference
in spread of the two spectra. The method requires the investigation
of a zone of uniform density. The shape of the autocorrelation
function of the photographic noise is obtained using an exploring
spot small enough not to cut off too much of the high frequencies of
the photographic noise. The plate is then investigated with the same
exploring spot, and the subtraction of the photographic noise is made
at the autocorrelation function.

---------------------------------------------------------
Title: Evidence for Large-Scale Oscillations of the Solar Photosphere
Authors: Fossat, E.; Ricort, G.; Aime, C.; Roddier, F.
1974ApJ...193L..97F Altcode:
Doppler shifts of the Na D1 line, averaged over large solar areas up to
the whole sun, have been recorded with a sodium resonance device. The
power spectra of the observed fluctuations show that (1) the 5-minute
oscillation has an horizontal coherence of 35,000 km at the level of
the sodium line formation; (2) the corresponding peak at 3.3 mHz is
not predominant for scales greater than 5'. New oscillations appear
with a 10-minute period.

---------------------------------------------------------
Title: Transformation in solar telescope of the Nice Observatory 40
cm coude refractor
Authors: Aime, C.; Demarcq, J.; Fossat, E.; Ricort, G.
1974NROpt...5..257A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Observation of the Solar Photospheric Oscillations Using a
Sodium Optical Resonance Device and an Optical Spatial Filtering
Authors: Fossat, E.
1974A&AS...15..475F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Contribution to the Observation of the Photospheric
Oscillations
Authors: Fossat, E.; Ricort, G.
1973SoPh...28..311F Altcode:
Observations of the 300 s photospheric oscillation on large solar
surfaces (up to 5'20″ in diameter) using a sodium optical resonance
cell seem to show that the power at long horizontal wavelengths
is larger than previous results would indicate. In order to get
more information about the spatial distribution of the energy, a new
observational method has been perfected, which will allow us to obtain
the spatiotemporal power spectrum.

---------------------------------------------------------
Title: A Sodium Experiment for Photospheric Velocity Field
Observations
Authors: Fossat, E.; Roddier, F.
1971SoPh...18..204F Altcode:
A method for studying small scale photospheric velocity fields with
a balloon experiment is proposed. A sodium resonance cell is used
with a diffraction limited telescope. Good pointing accuracy is not
necessary. Preliminary results of ground-based observations are given.

---------------------------------------------------------
Title: Mesures photographiques d'étoiles doubles
Authors: Fossat, Eric
1970A&AS....1..409F Altcode:
On donne 246 mesures photographiques de 95 couples, les cliche's
ayant ete' faits a' la lunette de 50 em de l'Observatoire de Nice,
la plupart avec Un agrandisseur de Barlow multipliant par trois la
longueur foe ale de l'instrnment, et quelques-uns au foyer direct.