Author name code: samain
ADS astronomy entries on 2022-09-14
author:Samain, D.
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Title: Recent Progress in Lunar Laser Ranging at Grasse Laser
Ranging Station
Authors: Chabé, Julien; Courde, Clément; Torre, Jean-Marie;
Bouquillon, Sébastien; Bourgoin, Adrien; Aimar, Mourad; Albanèse,
Dominique; Chauvineau, Bertrand; Mariey, Hervé; Martinot-Lagarde,
Grégoire; Maurice, Nicolas; Phung, Duy-Hà; Samain, Etienne; Viot,
Hervé
Bibcode: 2020E&SS....700785C
Altcode:
Based on a fully passive space segment, the lunar laser ranging
experiment is the last of the Apollo Lunar Surface Experiments Package
to operate. Observations from the Grasse lunar laser ranging station
have been made on a daily basis since the first echoes obtained in
1981. In this paper, first, we review the principle and the technical
aspects of lunar laser ranging. We then give a brief summary of the
progress made at the Grasse laser ranging facility (Observatoire de la
Côte d'Azur, Calern Plateau on the French Riviera) since the first
echoes. The current performance, driven by the use of an infrared
wavelength laser, is presented in the last section for the year 2018.
Title: Intensity interferometry revival on the Côte d'Azur
Authors: Lai, Olivier; Guerin, William; Vakili, Farrokh; Kaiser,
Robin; Rivet, Jean Pierre; Fouché, Mathilde; Labeyrie, Guillaume;
Chabé, Julien; Courde, Clément; Samain, Etienne; Vernet, David
Bibcode: 2018SPIE10701E..21L
Altcode: 2018arXiv181008023L
Recent advances in photonics have revived the interest in intensity
interferometry for astronomical applications. The success of
amplitude interferometry in the early 1970s, which is now mature
and producing spectacular astrophysical results (e.g. GRAVITY,
MATISSE, CHARA, etc.), coupled with the limited sensitivity of
intensity interferometry stalled any progress on this technique for
the past 50 years. However, the precise control of the optical path
difference in amplitude interferometry is constraining for very long
baselines and at shorter wavelengths. Polarization measurements are
also challenging in amplitude interferometry due to instrumental
effects. The fortuitous presence of strong groups in astronomical
interferometry and quantum optics at Université Côte d'Azur led
to the development of a prototype experiment at Calern Observatory,
allowing the measure of the temporal correlation g(2)(τ,
r=0) in 2016 and of the spatial correlation g(2)(r) in 2017
with a gain in sensitivity (normalized in observing time and collecting
area) of a factor 100 compared to Hanbury Brown and Twiss's original
Narrabri Interferometer. We present possible ways to further develop
this technique and point to. possible implementations on existing
facilities, such as CTA, the VLTI ATs or the summit of Maunakea,
which offer a unique scientific niche.
Title: Temperature, radiation and aging analysis of the DORIS
Ultra Stable Oscillator by means of the Time Transfer by Laser Link
experiment on Jason-2
Authors: Belli, Alexandre; Exertier, P.; Samain, E.; Courde, C.;
Vernotte, F.; Jayles, C.; Auriol, A.
Bibcode: 2016AdSpR..58.2589B
Altcode:
The Time Transfer by Laser Link (T2L2) experiment on-board the
Jason-2 satellite was launched in June 2008 at 1335 km altitude. It
has been designed to use the Satellite Laser Ranging (SLR) space
technique as an optical link between ground and space clocks. T2L2,
as all the instruments aboard Jason-2, is referenced to the Ultra
Stable Oscillator (USO) provided by the Doppler Orbitography and
Radio-positioning Integrated by Satellite (DORIS) system. A complex
data processing has been developed in order to extract time &
frequency products as the relative frequency bias of the USO from
ground-to-space time transfer passages. The precision of these products
was estimated of a few parts in 10-13 given the very good
in-flight performance of T2L2 with a ground-to-space time stability
of a few picoseconds (ps) over 100 s. Frequency bias from T2L2 were
compared with results from operational orbit computation, notably with
the DIODE (Détermination Immédiate d'Orbite par Doris Embarqué)
outputs (see Jayles et al. (2016) same issue) at the level of 1 ·
10-12. The present paper is focusing on the main
physical effects which drive the frequency variations of the Jason-2
USO during its flight, notably over the South Atlantic Anomaly (SAA)
area. In addition to the effects of radiation we studied the effect of
the residual temperature variations, in the range 8-11 °C (measured
on-board). A model was established to represent these effects on the
short term with empirical coefficients (sensitivities of the USO)
to be adjusted. The results of fitting the model over ∼200 10-day
periods, from 2008 to 2014, show the sensitivities of the Jason-2
USO to temperature and radiation. The analysis of the 6-year output
series of empirical coefficients allows us to conclude that: (i) the
temperature to frequency dependence is very stable along time at the
level of around -1.2 · 10-12 per °C, (ii) the radiation
effects are much lower than those previously detected on the Jason-1
USO with a factor > 10. The swept material used by manufacturers for
the Jason-2 quartz oscillator has such properties to avoid non-linear
effects >1-2 · 10-12, (iii) the model is available at 1
min or less over the Jason-2 mission, with a level of consistency of 5
· 10-13, which is the average RMS of the post-fit residuals.
Title: First on-sky results of the CO-SLIDAR Cn2 profiler
Authors: Voyez, Juliette; Robert, Clélia; Conan, Jean-Marc; Mugnier,
Laurent M.; Samain, Etienne; Ziad, Aziz
Bibcode: 2014OExpr..2210948V
Altcode: 2014arXiv1402.4295V
COupled SLope and scIntillation Detection And Ranging (CO-SLIDAR)
is a recent profiling method of the vertical distribution of
atmospheric turbulence strength ($C_n^2$ profile). It takes advantage
of correlations of slopes and of scintillation, both measured with a
Shack-Hartmann wavefront sensor on a binary star. In this paper, we
present the improved CO-SLIDAR reconstruction method of the $C_n^2$
profile and the first on-sky results of the CO-SLIDAR profiler. We
examine CO-SLIDAR latest performance in simulation, taking into account
the detection noise bias and estimating error bars along with the
turbulence profile. The estimated $C_n^2$ profiles demonstrate the
accuracy of the CO-SLIDAR method, showing sensitivity to both low and
high altitude turbulent layers. CO-SLIDAR is tested on-sky for the first
time, on the $1.5$~m MeO (Métrologie Optique) telescope at Observatoire
de la Cote d'Azur (France). The reconstructed profiles are compared
to turbulence profiles estimated from meteorological data and a good
agreement is found. We discuss CO-SLIDAR's contribution in the $C_n^2$
profilers' landscape and we propose some improvements of the instrument.
Title: Laser Ranging for Effective and Accurate Tracking of Space
Debris in Low Earth Orbits
Authors: Blanchet, Guillaume; Haag, Herve; Hennegrave, Laurent;
Assemat, Francois; Vial, Sophie; Samain, Etienne
Bibcode: 2013ESASP.723E..10B
Altcode:
The paper presents the results of preliminary design options for
an operational laser ranging system adapted to the measurement of
the distance of space debris. Thorough analysis of the operational
parameters is provided with identification of performance drivers
and assessment of enabling design options. Results from performance
simulation demonstrate how the range measurement enables improvement
of the orbit determination when combined with astrometry. Besides,
experimental results on rocket-stage class debris in LEO were obtained
by Astrium beginning of 2012, in collaboration with the Observatoire
de la Côte d'Azur (OCA), by operating an experimental laser ranging
system supported by the MéO (Métrologie Optique) telescope.
Title: First astrometric observations with the MéO telescope in
view of space debris observations
Authors: Laas-Bourez, Myrtille; Deleflie, Florent; Klotz, Alain;
Albanese, Dominique; Samain, Etienne
Bibcode: 2010cosp...38.3945L
Altcode: 2010cosp.meet.3945L
The MéO (for "Métrologie Optique") telescope is the Satellite and
Lunar Laser Ranging dedicated telescope of Observatoire de la Côte
d'Azur (France), and located at "plateau de Calern" (43,7546336886111
N 6,9215750911111 E 1323,3480 U). The telescope is pointed by an
altazimu-tale mount. The motorization, with a typical velocity of
5 deg/s allows to follow LEO satellites (from an altitude of 400
kilometers), as well as MEO and GEO satellites, and the Moon. The
telescope has an aperture of 1.54m. It has Nasmyth focus equipped
with an EMCCD camera. The field of view, defined by the equivalent
focal length and the size of the camera, is actually 3 arcmin x 3
arcmin. The paper aims at presenting two methods that we will be
developing to observe LEO and MEO satellites, and give very precise
astrometrical positions in view of testing the capabilities of such
an instrument to track space debris. In particular, the greater
diameter than the ones usually used for space debris tracking should
improve the current accu-racy of the observations within in the GEO
region. In the LEO region, such a diameter should allow to observe
trailing satellites with a high magnitude (to be quantified). The first
method is "stellar reference" -based. It consists in identifying stars
on the images sky background and in using an astrometrical catalog
to calibrate the passage relations between image coordinates and
celestial coordinates. The main difficulty comes from the possible
lack of catalogued stars on every image, to exactly identify, for
each track, the original epoch and positions of stellar trails. The
second method is "telescope referenced" -based. It consists in relying
the opto-mechanical chain of the telescope to assign the theoretical
value read in the ephemeris file as the center of the images. So,
we can calibrate the field blind. The difficulty consists hence in
estimating the accuracy of pointing of the telescope. The feasibility
of these two methods was demonstrated in January 2009. This paper
presents the methods used and the difficulties encountered. In the
second part we will introduce our first results obtained on LEO and MEO
satellites. In particular, we give an estimation of the astrometrical
error of the analysis scheme, by comparing for a couple of SLR geodetic
satellites the coordinates deduced from the data reduction strategy,
and the ones obtained from the orbit computation provided by the
International Laser Ranging Service.
Title: High-spectral-resolution solar irradiance in the 184.5 to
232.5 nm range from the SOLSPEC and UVSP spectrometers
Authors: Tartag, A.; Bénilan, Y.; Samain, D.; Thuillier, G.;
Bruston, P.
Bibcode: 2001SoPh..201..253T
Altcode:
The study of the minor constituents of the planetary atmospheres from
the analysis of the scattered light properties requires the knowledge of
the absolute incident solar irradiance at high resolution. The data were
obtained from the UVSP experiment on board the Solar Maximum Mission
satellite in the 184.5-232.5 nm spectral range. We have reconstituted
the solar spectrum measured in three different regions of the solar
disk with a spectral resolution of 0.01 nm and a spatial resolution
of 3 arc sec. The wavelength scale was determined with a standard
deviation of 0.0025 nm. The comparison of the relative intensities in
three locations of the solar disk with those obtained by other authors
allowed us to determine these positions accurately and to derive the
integrated spectrum of the whole disk. Finally, the resulting spectrum
has been expressed in absolute units using the spectral irradiance by
the SOLSPEC and SUSIM spectrometers, respectively operated with the
ATLAS 1 mission and from the Upper Atmosphere Research Satellite. We
obtained the absolute solar irradiance with an accuracy of 10% in the
184.5-232.5 nm spectral range with a spectral resolution of 0.01 nm
for the first time using data from space observations.
Title: Millimetric Lunar Laser Ranging at OCA (Observatoire de la
Cote d'Azur)
Authors: Samain, E.; Mangin, J. F.; Veillet, C.; Torre, J. M.;
Fridelance, P.; Chabaudie, J. E.; Feraudy, D.; Glentzlin, M.; Pham van,
J.; Furia, M.; Journet, A.; Vigouroux, G.
Bibcode: 1998A&AS..130..235S
Altcode:
The Lunar Laser Ranging station at the Observatoire de la Cote
d'Azur, France, permits to measure the Earth-Moon distance with
millimetric precision. Applications in astronomy, lunar science,
geodesy, and gravitation are summarised. Expected scientific results
with millimetric Lunar Laser Ranging data are presented. A complete
error budget is given, showing that the precision is mainly limited
by the orientation and the size of the corner cube arrays placed on
the Moon. The measurement accuracy is degraded by the bad knowledge
of the air index. The time stability, computed from the lunar echoes,
permits to extract the real precision of the Earth-Moon distance and
to optimise the integration time of the normal points.
Title: Erratum: "A high spectral resolution atlas of the balloon
ultraviolet spectrum of the Sun: 1950 - 2000 Å" [Astron. Astrophys.,
Suppl. Ser., Vol. 113, No. 2, p. 237 - 255 (Oct 1995)].
Authors: Samain, D.
Bibcode: 1998A&AS..127..353S
Altcode:
No abstract at ADS
Title: A high spectral resolution atlas of the balloon ultraviolet
spectrum of the Sun: 1950-2000 A.
Authors: Samain, D.
Bibcode: 1995A&AS..113..237S
Altcode:
An ultraviolet atlas of the solar spectrum with a spectral resolution of
15mA in the region 1948-2000A is presented. It is the first part of the
spectra recorded on the quiet Sun between 1900 and 2130A. Measurements
were performed from a balloon-borne instrumentation flown at an altitude
of 39km. The wavelength atlas with a list of about 550 lines has been
synthesized from data at center of the Sun (μ=1) and at μ=0.89,
smoothed out over an area of 30 arcsec. The wavelength scale is given
with respect to the average solar spectrum. Tracings are presented at
μ=0.89, with an intensity scale adjusted in absolute values on the
level of the continuum near 2000A.
Title: VizieR Online Data Catalog: Ultraviolet Spectrum of the Sun
(Samain, 1995)
Authors: Samain, D.
Bibcode: 1995yCat..41130237S
Altcode:
An ultraviolet atlas of the solar spectrum with a spectral resolution of
15mA in the region 1948-2000A is presented. It is the first part of the
spectra recorded on the quiet Sun between 1900 and 2130A. Measurements
were performed from a balloon-borne instrumentation flown at an altitude
of 39km. The wavelength atlas with a list of about 550 lines has been
synthesized from data at center of the Sun (μ=1) and at μ=0.89,
smoothed out over an area of 30 arcsec. The wavelength scale is given
with respect to the average solar spectrum. Tracings are presented at
μ=0.89, with an intensity scale adjusted in absolute values on the
level of the continuum near 2000A. (1 data file).
Title: A Preliminary Atlas of the Solar Balloon U. V. Spectrum of
the Quiet Sun
Authors: Samain, D.
Bibcode: 1994emsp.conf...99S
Altcode:
No abstract at ADS
Title: High Resolution Measurements of the 273-293 nm Solar Spectrum
from a Balloon Instrumentation
Authors: Lemaire, P.; Briand, C.; Staath, E.; Samain, D.
Bibcode: 1993BAAS...25.1221L
Altcode:
No abstract at ADS
Title: Photospheric lines redshift from balloon ultraviolet spectra
of the quiet Sun
Authors: Samain, D.
Bibcode: 1991ESASP.317..363S
Altcode: 1991erbp.symp..363S
Wavelength shifts between solar photospheric lines observed in two quiet
areas of the Sun and telluric O2 absorption lines of the Schulman-Runge
bands were measured in the 1950 to 2000 A region. The results are
deduced from high resolution spectra taken on board a balloon experiment
at an altitude of 39 km. They show a systematic redshift of the solar
lines relative to the reference telluric spectrum. After correction
for the gravitational redshift and for all the known relative motions
between Sun and observer, the average residual value is +7 mA, that
corresponds in terms of velocity to an equivalent Doppler-Fizeau shift
on the whole spectrum of about 1 km/s away from the observer. Whether
the redshift has a solar origin or the O2 telluric lines are blueshifted
in the terrestrial atmosphere is considered
Title: Is the ultraviolet spectrum of the quiet sun redshifted?
Authors: Samain, D.
Bibcode: 1991A&A...244..217S
Altcode:
A wavelength shift between the Fraunhofer spectrum observed in two
quiet areas of the sun and the superimposed telluric absorption
spectrum of the Schuman-Runge bands due to O2 has been measured in
the wavelength region 1950-2000 A. The results deduced from high
resolution spectra taken on board a balloon experiment at an altitude
of 39 km are presented. They show a systematic redshift of the solar
lines relative to the reference telluric spectrum. After correction
for the gravitational redshift and for all the known relative motions
between sun and observer, the average residual redshift is 7 mA and
could be from 5 to 12 mA for some individual reference lines. This
corresponds in terms of velocity to an equivalent Doppler-Fizeau shift
on the whole spectrum of about 1 km/s away from the observer.
Title: Fine structure observation in a solar prominence
Authors: Lemaire, P.; Samain, D.; Vial, J. C.
Bibcode: 1990AdSpR..10i.191L
Altcode: 1990AdSpR..10..191L
The high resolution balloon spectrograph (RASOLBA) has obtained
ultraviolet prominence spectra during its September 19th, 1986,
flight. The high resolution spectra (one arcsecond along the
30 arcseconds spectrograph slit length, and 0.0015 nm spectral
resolution within the 20 nm wavelength band) have been recorded on
film. The wavelength band was centered on the Mgll h and k (279.6
nm and 280.3 nm) resonance doublet lines inside the cross-dispersion
echelle spectrograph. The analysis of the prominence spectra shows
evidence of sheared velocities (up to 20 km/s) which very within few
arcseconds with the distance above the limb. This shear may appear
inside magnetic loops confining the prominence material. We present
the observations and a preliminary analysis of the data.
Title: High resolution observations of the solar UV spectrum from
balloon
Authors: Lemaire, P.; Samain, D.
Bibcode: 1989hsrs.conf..551L
Altcode:
No abstract at ADS
Title: Solar Ultraviolet Spectrum Obtained from a Balloon Gondola
Authors: Samain, D.; Lemaire, P.
Bibcode: 1987ESASP.270..347S
Altcode: 1987erbp.symp..347S
A new flight of the L.P.S.P. balloon experiment on September 19, 1986
has permitted the recording of high resolution photographic spectra in
the 2800 Å channel (1 arcsec and 15 mÅ). Several time sequences at Sun
center, limb, intermediate location (μ = 0.5) and on a prominence have
been performed; some of these results are presented. Data reduction
of the high spectral resolution spectra recorded in 1982 has been
completed for the region 1950-2000 Å, in which many features have
been measured and tabulated; one of these detailed tracings is given
and some results on wavelength shifts analysed.
Title: Balloon-Borne Ultraviolet Solar Telescope and High Resolution
Echelle Spectrograph - Instrumentation and First Results
Authors: Samain, D.; Lemaire, P.
Bibcode: 1985Ap&SS.115..227S
Altcode:
A description of the LPSP balloon-borne telescope — spectrograph
combination is given. The payload comprises a one-axis stabilized
platform carrying a two-axes equatorial pointing system; the
instrumentation directed towards the Sun is a 300 mm telescope coupled
with an echelle spectrograph and a slit jaw camera. The scientific
objective of the experimental set-up is to observe spatial, spectral,
and temporal variations of fine structures of the solar atmosphere,
using ballon ultraviolet windows between 190 and 300 nm, with very
high angular and spectral resolutions (0.5 arc sec and 1 pm). In the
configuration of the first flight which successfully took place on 1
October, 1982 from Aire-sur'l'Adour (Landes), many stigmatic spectra
of the Sun were recorded in the 190 213 and 272 293 nm ranges, with
an angular resolution of 4 arc sec and a spectral resolution of 1.5
to 2 pm.
Title: Solar High Resolution Balloon Spectra Obtained in the 190-300
nm Wavelength Band
Authors: Samain, D.; Lemaire, P.
Bibcode: 1985LNP...233..123S
Altcode: 1985hrsp.proc..123S
A balloon gondola with a solar telescope spectrograph has been
launched from Aire/Adour (France) October 1, 1982. High quality
spectra with a spectral resolution better than 1.5 pm and with a 4 -
5 arcseconds angular resolution have been recorded in the atmospheric
window domains: 195 - 212 nm and 272 - 292 nm. Results from this first
flight are discussed.
Title: Solar high resolution balloon spectra obtained in the 190-300
nm wavelength band
Authors: Lemaire, P.; Samain, D.
Bibcode: 1984AdSpR...4h..37L
Altcode: 1984AdSpR...4...37L
To obtain solar high-resolution balloon spectra in the 190-300
nm wavelength range outside of the strong absorption ozone
band, a new solar instrumentation and an equatorial mounting
platform are developed. The instrumentation, which consists of a
telescope-spectrograph combination, and its characteristics are
described. Observations are made at an altitude of 38 km and two
sequences of spectra are taken near sun center, one on a supergranular
cell and the other one over an active network. The spectra recorded
during the flight show an intensity variation related to the wavelength
dependance of atmospheric transmission. The results obtained in two
wavelength domains (190-210 nm and 272-283 nm) during the first balloon
flight are presented and discussed. The spectral resolution is found
to be better than 2 pm in the 200 nm range and better than 1.5 pm in
the 280 nm range; and the angular resolution is found to be about
5 arcsec. Calibration in intensity is made by comparison to rocket
spectra. Stigmatic line profiles illustrate the results.
Title: A high-resolution ultraviolet solar telescope/spectrograph
mounted on an equatorial balloon platform
Authors: Samain, D.; Lemaire, P.
Bibcode: 1983ESASP.183..401S
Altcode:
A balloon-borne 30 cm telescope-spectrograph combination was built
to observe fine structures of the solar atmosphere with very high
spectral and angular resolution in two atmospheric windows: 2700 to
2950 A and 1900 to 2300 A. Solar spectra with spectral resolution of
15 mA and angular resolution of 4 arcsec were recorded.
Title: Solar ultraviolet continuum radiation - The photosphere,
the low chromosphere, and the temperature-minimum region
Authors: Samain, D.
Bibcode: 1980ApJS...44..273S
Altcode:
Solar disk-center intensity measurements are compared with theoretical
values calculated for atmospheric models derived from the temperature
distributions found by Vernazza et al (1976); generally good agreement
is found with an atmospheric model having a minimum temperature of
about 4150 K or possibly higher. Empirical opacity values including
LTE departures and absorption coefficients which best represent the
radiation field in the range 1460-2100 A are presented. It is shown
that a contribution to the opacity from Fe I almost equal to the Si
I opacity makes it possible to explain the observed center-to-limb
contrast between 1525 and 1570 A and its fast change through 1570
A. However, the strong measured limb darkening as compared with
the calculated variation from 1600 to 1682 A cannot completely be
accounted for in terms of opacity and still preserve the agreement
with the absolute center intensities.
Title: Solar continuum data on absolute intensities, center to limb
variations and Laplace inversion between 1400 and 2100 Å.
Authors: Samain, D.
Bibcode: 1979A&A....74..225S
Altcode:
No abstract at ADS
Title: Development of a High Resolution Ultraviolet Solar Spectrograph
to BE Launched on a Balloon Equatorial Platform
Authors: Lemaire, P.; Samain, D.
Bibcode: 1978ESASP.135..283L
Altcode: 1978esrb.rept..283L
A telescope-spectrometer instrumentation to study the sun in the
spectral ranges 1950-2200 A and 2650-2900 A is being developed to
obtain spatial, spectral, and time information on quiet and active
fine structures of the solar photosphere-chromosphere zone. To achieve
these objectives, an instrumentation able to give 0.5 arcsec angular
resolution on the solar surface and 0.01 A spectral resolution was
studied.
Title: Solar flux determination in the spectral range 150 210 nm
Authors: Samain, D.; Simon, P. C.
Bibcode: 1976SoPh...49...33S
Altcode:
Solar irradiation fluxes are determined between 150 and 210 nm from
stigmatic spectra of the Sun obtained by means of a rocket-borne
spectrograph. Absolute intensities at the disk center with a spectral
resolution of 0.04 nm and a spatial resolution of 7 arc sec are
presented. From center-to-limb intensity variations determined from
the same spectra, mean full disk intensities of the quiet Sun can be
deduced. In order to compare them with other measurements, the new
solar fluxes have been averaged over a bandpass of 1 nm.
Title: Stigmatic spectra of the sun between 1200 Å and 2100 Å.
Authors: Samain, D.; Bonnet, R. M.; Gayet, R.; Lizambert, C.
Bibcode: 1975A&A....39...71S
Altcode:
Stigmatic spectra of the sun from 1200 to 2100 A, with spatial
resolution on the disk of 7 arc sec, have been obtained during a rocket
flight on April 17, 1973 from Kourou, French Guiana. The mean spectral
resolution achieved is 0.4A. Absolute intensities and center-to-limb
variations of the solar UV continuum have been measured on both sides
of the temperature minimum. They locate the position of this minimum
around 1580 A with a value of 4430 (plus or minus 50) K. It is shown
that these are upper limits and are not necessarily incompatible with
infrared observations which lead to lower values. It is shown that
an extra opacity is required to represent the observations down to,
at least, 1580 A.
Title: Observations de la raie d'émission de C I dans le spectre
solaire à 1993.6 Å.
Authors: Samain, D.
Bibcode: 1971CRASB.273.1133S
Altcode:
No abstract at ADS