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Author name code: penn
ADS astronomy entries on 2022-09-14
author:"Penn, Matthew"
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Title: SEARCH: SEgmentation of polAR Coronal Holes
Authors: Tiwari, Ajay Kumar; Tremblay, Benoit; Hu, Andong; Wolniewicz,
Linnea M.; Kirk, Michael; Guidoni, Silvina; Smith, Brent; Penn,
Matthew; Samanta, Tanmoy
2021csss.confE.211T Altcode:
The identification of solar coronal holes (CHs) observed in Extreme
Ultraviolet (EUV) intensity images of the Sun is key in improving
our understanding of their association with solar magnetic fields
and heliophysics. In particular, CHs at the poles of the Sun are a
notorious source of fast solar wind and thus warrant further study,
most notably in the context of space-weather forecasting. This has
consequently led to the development of various segmentation methods
for their identification, including supervised machine learning. We
introduce the SEARCH project to combine EUV data from the three vantage
points (e.g., STEREO-A, STEREO-B, and SoHO) during the 2010-2014
epoch to produce synchronic maps and apply unsupervised learning
methods including clustering and convolutional neural networks for
the segmentation of CHs. SEARCH segmentation maps provide a venue to
explore the relationship between CH pole areas, geomagnetic activity,
and the magnetic activity cycle (dynamo process) of the Sun and Sun-like
stars. Finally, in addition to CHs, the unsupervised learning methods
we tested identified features consistent with active regions.
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Title: Acceleration of Coronal Mass Ejection Plasma in the Low Corona
as Measured by the Citizen CATE Experiment
Authors: Penn, Matthew J.; Baer, Robert; Walter, Donald; Pierce,
Michael; Gelderman, Richard; Ursache, Andrei; Elmore, David; Mitchell,
Adrianna; Kovac, Sarah; Hare, Honor; McKay, Myles; Jensen, Logan;
Watson, Zachary; Conley, Mike; Powers, Lynn; Lazarova, Marianna;
Wright, Joseph; Young, David; Isberner, Fred; Hart, C. Alexandra;
Sheeley, N. R., Jr.; Penn, Debbie; Allen-Penn, Kate; Alder, Bruce;
Alder, Ryan; Hall-Conley, Geri; Gerdes, David; Weber, Katherine;
Johnson, Jeffrey; Matzek, Gerald; Somes, Steven; Sobnosky, Rob;
McGowen, Robert; Meo, Michael; Proctor, Damani; Wessinger, Charlie;
Schilling, Jeannine; Kerr, Jay; Beltzer-Sweeney, Alexander; Falatoun,
Alex; Higgins, David; Boyce, Grady; Hettick, Jared; Blanco, Philip;
Dixon, Scott; Ardebilianfard, Sepehr; Boyce, Pat; Lighthill, Richard;
Lighthill, Denese; Anderson, David; Anderson, Mine; Schad, Thomas;
Smith, Sonna; Jensen, Declan; Allen, Anthony; Smith, Donavan; Brandon,
Gage; Earp, Joe; Earp, Jane; Blair, Bob; Claver, Chuck F.; Claver,
Jennifer A.; Claver, Ryan H.; Hoops, Danielle; Rivera, Esteban;
Gibson, Llanee; Hiner, Martin; Lann, Rein; Miller, Shaedyn; Briggs,
Burton; Davis, Karan; Jackson, Brian; Kautzsch, Kaleb; Sandidge,
Wesley; Lucas, Russell; Gregg, Duane; Kamenetzky, Julia; Rivera,
Tiffany; Shaw, Joe; Scherrer, Bryan; Sandbak, Dylan; McFate, Richard;
Harris, Wilson; Brasier, Zachery; McNeil, Stephen; Jensen, Jack;
Jensen, Makai; Moore, Mason; Temple, Alexandria; Vanderhorst, Thomas;
Kautz, Richard; Bellorado, Orion; Jenkins, LaVor R.; Pantuso, Corey;
Carey, Marley; Byrnes, Josh; Scholtens, Kyle; Web, Julian; Baker,
Brain; Barngrover, Katie; Hathaway, Drew; Smith, Kallen; Chandler,
Kellyn; Hinkle, Lydia; Chandler, Ione; Gisler, Galen; Benner, Jack;
Mas, Madison; Rogers, Maya; Moore, Prescott; Pelofske, Elijah;
Gulley, Stephen; Short, Beth; Crooker, Isabel; Hammock, Jennifer;
Cardenas, Katsina; Cardenas, Kateri; Wellman, Jennifer; Roy, Mark;
Meyer, Joe; Brough, Jalynne; Brough, Kameron; Nelson, Tim; Nelson,
Zack; Russell, Caleb; Bautz, Theresa; Weitzel, Eric; Team; Wistisen,
Michele; Aagard, Shae; Whipps, Zachary; Neuroth, Logan; Poste, Dawson;
Worthen, Connor; Gosain, Sanjay; Steward, Mark; Gosain, Vanshita;
Gosain, Ruchi; Jorgensen, Janet; Doucette, Eleanor; Doucette, Reba;
Iwen, Elliott; Cochran, Alexus; Stith, James; Scribner, Doug; Kenney,
Austen; Pisciotti, Kolby; Pease, Irene; Cynamon, Samuel; Cynamon,
Charles; Cynamon, Dawn; Tolbert, Bart; Dupree, Jean A.; Weremeichik,
Jeremy; Pindell, Nathan; Stives, Kristen; Simacek, Thomas K.; Simacek,
Yolanta G.; Simacek, Anne L.; Boeck, Wayne; Boeck, Andreea; Ryan,
Austin; Wierzorec, Gabriel; Klebe, Dimitri; Costanza, Bryan; Cerny,
Arnie; Schmale, Trevor; Hoffman, Tessa; Streeter, Sam; Erickson,
Jack; McClellan, Michele; Erickson, Ella; Brettell, Brynn; Shoffner,
Savannah; McClellan, Emilie; VanVoorhis, Julie; Bramhall, Cole; Stelly,
Daniel; Bee, Bentley; Acevedo, Bruno; Kroeger, Madison; Trumpenski,
Ben; Sump, Nolan; Brook, Liam; Ernzen, Jagert; Lewis, Jessica;
Maderak, Ryan; Kennedy, Charles; Dembinski, David; Wright, Rita;
Foster, Michael; Ahmadbasir, Mohammad; Laycox, Monty; Foster, James;
Orr, Ethan; Staab, Ashley; Speck, Angela; Baldridge, Sean; Kegley,
Lucy; Bavlnka, Jordan; Ballew, Thomas; Callen, Bruce; Ojakangas,
Gregory; Bremer, Mark; Angliongto, Maryanne; Redecker, Mark; Bremer,
Chris; Hill, Peggy; Rodgers, Michael; Duncan, Jordan; Fincher, Sam;
Nielsen, Ben; Hasler, Samantha; Shivelbine, Taylor; Howard, Tyler;
Midden, Chris; Patrick, Sean; Glenn, Kerry; Mandrell, Chris; Dawson,
Kyle; Cortez, Margaret; Levsky, Alyssa; Gallaba, Dinuka; Perrone,
Mason; Taylor, Jasmyn; Yanamandra-Fisher, Padma A.; Harper, Howard;
Adams, Lindsay; Springer, Michaela; Menard, BillyJoe; Boggs, Dylan;
Lynch, Caitlin; Watson, Jacob; York, Andi; Matthews, David; Brown,
Kiley; Garrison, Dylan; Mangin, Jonathan; Mangin, Isaac; Birriel,
Jennifer; Birriel, Ignacio; Yess, Capp; Anderson, Jesse; Caudill,
Ethan; Smith, Allyn; Buckner, Spencer; Longhurst, Russ; Fagan, Ben;
Nations, Christian; DiMatties, Jeffrey; Thompson, Patricia; Garrison,
David; Garrison, Thomas; Garrison, William; Kidd, Mary; Baker, Maria;
Ledford, Mary-Beth; Winebarger, Amy; Freed, Michael; Church, Morgyn;
Dickens, Jim; Anderson, Bob; Smith, Ned; Dorsey, Lynne; Justice, Doug;
Zavala, Daniel; Stockbridge, Zach; Brittain, Sean; Jensen, Stanley;
Leiendecker, Harrison; Thompson, Erin; Deady, Michelle; Quinn-Hughes,
Kelly; Slimmer, David; Granger, Valerie; LaRoche, Michael; Hill
LaRoche, Serena; Manspeaker, Rachel; Nguyen, Peter; Smith, Daniel;
Payne, Jim; Zissett, Jerry; Roberts, Arianna M.; Roberts, Gabrielle
W.; Roberts, Harrison; Riddle, Amy; Ursache, Corina; Ursache, Elena
2020PASP..132a4201P Altcode:
The citizen Continental-America Telescopic Eclipse (CATE) Experiment
was a new type of citizen science experiment designed to capture a time
sequence of white-light coronal observations during totality from 17:16
to 18:48 UT on 2017 August 21. Using identical instruments the CATE
group imaged the inner corona from 1 to 2.1 RSun with 1.″43 pixels
at a cadence of 2.1 s. A slow coronal mass ejection (CME) started on
the SW limb of the Sun before the total eclipse began. An analysis
of CATE data from 17:22 to 17:39 UT maps the spatial distribution of
coronal flow velocities from about 1.2 to 2.1 RSun, and shows the CME
material accelerates from about 0 to 200 km s<SUP>-1</SUP> across this
part of the corona. This CME is observed by LASCO C2 at 3.1-13 RSun
with a constant speed of 254 km s<SUP>-1</SUP>. The CATE and LASCO
observations are not fit by either constant acceleration nor spatially
uniform velocity change, and so the CME acceleration mechanism must
produce variable acceleration in this region of the corona.
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Title: First results from the Citizen CATE Experiment from August 2017
Authors: Penn, Matthew; Citizen CATE Experiment 2017 Team
2018AAS...23122005P Altcode:
The Citizen Continental-America Telescopic Eclipse Experiment deployed
68 identical telescope/detector systems across the path of totality for
the August 2017 solar eclipse. The sites were located from Oregon to
South Carolina, and while at any one site the solar corona was observed
for just 2 minutes, the combined data set reveals evolution of the
corona for 93 minutes of time. CATE aims to measure the acceleration
of the fast solar wind in polar plumes, which is currently unknown
as the inner solar corona is not observed from space and difficult to
observe at high signal to noise from the ground. With radial velocities
ranging from 1 to 100 km/s, density enhancements in the wind in the
polar plumes should be observed to move across the CATE field of view
in about 1 hour.On 21 Aug 2017, the CATE network had fantastic luck,
collecting data from more than 56 of the 68 sites, and excellent
data was collected at the first and last sites, maximizing the time
coverage. Several of the volunteers from 27 universities, 22 high
schools and 19 amateur astronomers uploaded one high-dynamic range
image on eclipse day and an initial movie of the coronal evolution
has been made (https://citizencate.org ). Polar plumes are observed
in the CATE data to the edge of the field above both north and south
polar coronal holes. Slow evolution of low-lying coronal loops is
seen, and large-scale motions are visible in a coronal streamer
on the south-east solar limb. An ejection event is observed in the
southern coronal hole, but with just 1% of the data analyzed so far,
the signal to noise ratio is currently not sufficient to track steady
solar wind flows.CATE was funded with a collaboration of federal,
corporate and private groups. CATE training was funded by NASA, and
CATE equipment was funded by Daystar, Mathworks, Celestron, colorMaker,
NSF and a dozen smaller donors. The funding was organized so that all
68 CATE groups are keeping their equipment, and CATE is now seeking
other types of citizen science projects in astronomy. Please bring
your project ideas to the talk!
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Title: The Citizen CATE Experiment: Techniques to Determine Totality
Coverage and Clouded Data Removal.
Authors: McKay, Myles A.; Ursache, Andrei; Penn, Matthew; Citizen
CATE Experiment 2017 Team
2018AAS...23124206M Altcode:
August 21, 2017, the Citizen Continental-America Telescopic
Eclipse(CATE) Experiment observed the 2017 total solar eclipse using
a network of 68 identical telescopes and camera systems along the path
of totality. The result from the observation was over 90% of all sites
collected totality data on the day of the eclipse. Since the volunteers
had to remove the solar filter manually, there is an uncertainty between
the time of totality and data acquired during totality. Some sites also
experienced cloudy weather which obscured the eclipse in some of the
exposures but had small breaks in the clouds during the observation,
collecting clear totality data. Before we can process and analyze the
eclipse data, we must carefully determine which frames cover the time
of totality for each site and remove exposures with clouds blocking
the FOV. In this poster, we will discuss the techniques we used to
determine the extent of totality from each location using the logged
GPS data and the removal of totality exposure with clouds.
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Title: Preparing a Nation for the Eclipse of a Generation -
Authors: Speck, Angela; Habbal, Shadia; Tresch Fienberg, Richard;
Kentrianakis, Michael; Fraknoi, Andrew; Nordgren, Tyler; Penn,
Matthew; Pasachoff, Jay M.; Bakich, Michael; Winter, Henry; Gay,
Pamela; Motta, Mario
2018AAS...23122002S Altcode:
On August 21st 2017, there was a total solar eclipse visible from
a vast swath of the US.In preparation for that event, the American
Astronomical society created a taskforce charged with planning
for the eclipse for the entire nation. The preparations included
interfacing with the public, the media, non-profit organizations and
governmental organizations. Preliminary data suggests that nearly 90%
of American adults watched the eclipse either directly or via live
streams. Moreover, there were no major problems associated with the
event, in spite of valiant attempts from, e.g. imprope solar viewing
materials. The eclipse offered opportunities for many scientific
experiments within and ebyond astronomy. Here we present on the work
of the taskforce, and the lessons learned as well as lesser known
science experiments undertaken during the eclipse.
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Title: Polarization Observations of the Total Solar Eclipse of August
21, 2017
Authors: Burkepile, J.; Boll, A.; Casini, R.; de Toma, G.; Elmore,
D. F.; Gibson, K. L.; Judge, P. G.; Mitchell, A. M.; Penn, M.; Sewell,
S. D.; Tomczyk, S.; Yanamandra-Fisher, P. A.
2017AGUFMSH13B2477B Altcode:
A total solar eclipse offers ideal sky conditions for viewing the
solar corona. Light from the corona is composed of three components:
the E-corona, made up of spectral emission lines produced by ionized
elements in the corona; the K-corona, produced by photospheric light
that is Thomson scattered by coronal electrons; and the F-corona,
produced by sunlight scattered from dust particles in the near
Sun environment and in interplanetary space. Polarized white light
observations of the corona provide a way of isolating the K-corona to
determine its structure, brightness, and density. This work focuses
on broadband white light polarization observations of the corona
during the upcoming solar eclipse from three different instruments. We
compare coronal polarization brightness observations of the August 21,
2017 total solar eclipse from the NCAR/High Altitude Observatory (HAO)
Rosetta Stone experiment using the 4-D Technology PolarCam camera with
the two Citizen PACA_CATE17Pol telescopes that will acquire linear
polarization observations of the eclipse and the NCAR/HAO K-Cor white
light coronagraph observations from the Mauna Loa Solar Observatory in
Hawaii. This comparison includes a discussion of the cross-calibration
of the different instruments and reports the results of the coronal
polarization brightness and electron density of the corona. These
observations will be compared with results from previous coronal
measurements taken at different phases of the solar cycle. In addition,
we report on the performance of the three different polarimeters. The
4-D PolarCam uses a linear polarizer array, PACA_CATE17Pol uses
a nematic liquid crystal retarder in a single beam configuration
and K-Cor uses a pair of ferroelectric liquid crystal retarders in
a dual-beam configuration. The use of the 4-D PolarCam camera in the
Rosetta Stone experiment is to demonstrate the technology for acquiring
high cadence polarization measurements. The Rosetta Stone experiment
is funded through the NASA award NNH16ZDA001N-ISE. The Citizen Science
approach to measuring the polarized solar corona during the eclipse
is funded through NASA award NNX17AH76G. The NCAR Mauna Loa Solar
Observatory is funded by the National Science Foundation.
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Title: First results from the Citizen CATE Experiment 2017
Authors: Penn, M. J.
2017AGUFMSH24A..03P Altcode:
The Citizen Continental-America Telescopic Eclipse (CATE) Experiment
will monitor the corona using a network of 68 identical telescopes
positioned along the path of totality on 21 August 2017. The individual
high quality images taken during the 2 minutes of totality at each
site will be combined to create a uninterrupted 93 minute sequence
of the inner solar corona. CATE data will image the inner corona
in white light using wavelengths between 480nm and 680nm. With 1.5
arcsec pixels, the transverse velocity sensitivity will be roughly from
1-150 km/s. Sites will collect a sequence of 8 exposures from 0.4 msec
up to 1.3 sec duration, and these exposures will be used to produce
one high-dynamic range image every 2.1 seconds. The expected signal
to noise ratio in the data should allow brightness fluctuations of
about 5% to be detected. The initial science goal is to measure the
solar wind velocity and acceleration in polar plumes as the plasma
accelerates from 1 to 100 km/s in the CATE field-of-view.
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Title: Critical Infrared Science with the Daniel K. Inouye Solar
Telescope
Authors: Schad, Thomas A.; Fehlmann, Andre; Jaeggli, Sarah A.; Kuhn,
Jeffrey Richard; Lin, Haosheng; Penn, Matthew J.; Rimmele, Thomas R.;
Woeger, Friedrich
2017SPD....4811703S Altcode:
Critical science planning for early operations of the Daniel K. Inouye
Solar Telescope is underway. With its large aperture, all-reflective
telescope design, and advanced instrumentation, DKIST provides
unprecedented access to the important infrared (IR) solar spectrum
between 1 and 5 microns. Breakthrough IR capabilities in coronal
polarimetry will sense the coronal magnetic field routinely for the
first time. The increased Zeeman resolution near the photospheric
opacity minimum will provide our deepest and most sensitive measurement
of quiet sun and active region magnetic fields to date. High-sensitivity
He I triplet polarimetry will dynamically probe the chromospheric
magnetic field in fibrils, spicules, and filaments, while observations
of molecular CO transitions will characterize the coolest regions
of the solar atmosphere. When combined with the longer timescales
of good atmospheric seeing compared with the visible, DKIST infrared
diagnostics are expected to be mainstays of solar physics in the DKIST
era. This paper will summarize the critical science areas addressed
by DKIST infrared instrumentation and invite the community to further
contribute to critical infrared science planning.
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Title: The thermal infrared continuum in solar flares
Authors: Fletcher, Lyndsay; Simoes, Paulo; Kerr, Graham Stewart;
Hudson, Hugh S.; Gimenez de Castro, C. Guillermo; Penn, Matthew J.
2017SPD....4810821F Altcode:
Observations of the Sun with the Atacama Large Millimeter Array have
now started, and the thermal infrared will regularly be accessible
from the NSF’s Daniel K. Inouye Solar Telescope. Motivated by the
prospect of these new observations, and by recent flare detections in
the mid infrared, we set out here to model and understand the source
of the infrared continuum in flares, and to explore its diagnostic
capability for the physical conditions in the flare atmosphere. We use
the 1D radiation hydrodynamics code RADYN to calculate mid-infrared
continuum emission from model atmospheres undergoing sudden deposition
of energy by non-thermal electrons. We identify and characterise the
main continuum thermal emission processes relevant to flare intensity
enhancement in the mid- to far-infrared (2-200 micron) spectral range
as free-free emission on neutrals and ions. We find that the infrared
intensity evolution tracks the energy input to within a second,
albeit with a lingering intensity enhancement, and provides a very
direct indication of the evolution of the atmospheric ionization. The
prediction of highly impulsive emission means that, on these timescales,
the atmospheric hydrodynamics need not be considered in analysing the
mid-IR signatures.
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Title: Multi-site Observations of the March 2016 Total Solar Eclipse:
Calibration of Images to Simulate Continuous Monitoring
Authors: Bosh, Robert; Penn, Matthew J.; McKay, Myles; Baer, Robert;
Garrison, David; Gelderman, Richard; Hare, Honor; Isberner, Fred;
Jensen, Logan; Kovac, Sarah; Mitchell, Adriana; Pierce, Michael;
Thompson, Patricia; Ursache, Andrei; Varsik, John R.; Walter, Donald
K.; Watson, Zachary; Young, David; Citizen Cate Team
2017AAS...22942401B Altcode:
During the total solar eclipse of March 9, 2016, five teams of
astronomers participating in the Citizen Continental America Telescopic
Eclipse (CATE) experiment, traveled to different locations in Indonesia
to observe the eclipse. Data was acquired to continuously monitor the
progression of features in the inner solar corona: a region of the
solar atmosphere where time evolution is not well understood. Image
data from the eclipse consisted of sets of 7 exposure times 0.4, 1.3,
4, 13, 40, 130, and 400 milliseconds which are used to create a high
dynamic range composite image. Eclipse data from these sites were then
processed and calibrated using sets of dark and flat images. Further
data processing included the compilation of exposures into high dynamic
range images and were subsequently spatially filtered. Using these
processing techniques, data from each site was aligned and compiled
as frames in videos of the eclipse, each consisting of over 140 frames
with the goal of being combined. Lessons learned from the data obtained
in the observations of the 2016 total solar eclipse are being used to
improve the procedure which will be used in the CATE experiment during
the North American 2017 total solar eclipse.
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Title: Instrumentation for the Citizen CATE Experiment: Faroe Islands
and Indonesia
Authors: Penn, M. J.; Baer, R.; Bosh, R.; Garrison, D.; Gelderman, R.;
Hare, H.; Isberner, F.; Jensen, L.; Kovac, S.; McKay, M.; Mitchell,
A.; Pierce, M.; Thompson, P.; Ursache, A.; Varsik, J.; Walter, D.;
Watson, Z.; Young, D.; Citizen CATE Team
2017PASP..129a5005P Altcode: 2016arXiv160900035P
The inner regions of the solar corona from 1-2.5 Rsun are poorly
sampled both from the ground and space telescopes. A solar eclipse
reduces the sky scattered background intensity by a factor of about
10,000 and opens a window to view this region directly. The goal of the
Citizen Continental-America Telescopic Eclipse (CATE) Experiment is to
take a 90-minute time sequence of calibrated white-light images of this
coronal region using 60 identical telescopes spread from Oregon to South
Carolina during the 2017 August 21 total solar eclipse. Observations
that can address questions of coronal dynamics in this region can be
collected with rather modest telescope equipment, but the large dynamic
range of the coronal brightness requires careful camera control. The
instruments used for test runs on the Faroe Islands in 2015 and at five
sites in Indonesia in 2016 are described. Intensity calibration of the
coronal images is done and compared with previous eclipse measurements
from November & Koutchmy and Bazin et al. The change of coronal
brightness with distance from the Sun seen in the 2016 eclipse agrees
with observations from the 1991 eclipse, but differ substantially
from the 2010 eclipse. The 2015 observations agree with 2016 and 1991
solar radii near the Sun, but are fainter at larger distances. Problems
encountered during these test runs are discussed as well the solutions
which will be implemented for the 2017 eclipse experiment.
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Title: Vector Magnetic Field Measurements along a Cooled Stereo-imaged
Coronal Loop
Authors: Schad, T. A.; Penn, M. J.; Lin, H.; Judge, P. G.
2016ApJ...833....5S Altcode: 2016arXiv161005332S
The variation of the vector magnetic field along structures in
the solar corona remains unmeasured. Using a unique combination of
spectropolarimetry and stereoscopy, we infer and compare the vector
magnetic field structure and three-dimensional morphology of an
individuated coronal loop structure undergoing a thermal instability. We
analyze spectropolarimetric data of the He I λ10830 triplet
(1s2s{}<SUP>3</SUP>{S}<SUB>1</SUB>-1s2p{}<SUP>3</SUP>{P}<SUB>{2,1,0</SUB>})
obtained at the Dunn Solar Telescope with the Facility Infrared
Spectropolarimeter on 2011 September 19. Cool coronal loops are
identified by their prominent drainage signatures in the He I data
(redshifts up to 185 km s<SUP>-1</SUP>). Extinction of EUV background
radiation along these loops is observed by both the Atmospheric Imaging
Assembly on board the Solar Dynamics Observatory and the Extreme
Ultraviolet Imager on board spacecraft A of the Solar Terrestrial
Relations Observatory, and is used to stereoscopically triangulate
the loop geometry up to heights of 70 Mm (0.1R <SUB>Sun</SUB>) above
the solar surface. The He I polarized spectra along this loop exhibit
signatures indicative of atomic-level polarization, as well as magnetic
signatures through the Hanle and Zeeman effects. Spectropolarimetric
inversions indicate that the magnetic field is generally oriented
along the coronal loop axis, and provide the height dependence of the
magnetic field intensity. The technique we demonstrate is a powerful
one that may help better understand the thermodynamics of coronal
fine-structure magnetism.
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Title: Spectropolarimetry of Atomic and Molecular Lines near 4135 nm
Authors: Penn, Matthew James; Uitenbroek, Han; Clark, Alan; Coulter,
Roy; Goode, Phil; Cao, Wenda
2016SoPh..291.2243P Altcode: 2015arXiv151204451P; 2016SoPh..tmp..142P
New spatially scanned spectropolarimetry sunspot observations are made
of photospheric atomic and molecular absorption lines near 4135 nm. The
relative splittings among several atomic lines are measured and shown
to agree with values calculated with configuration interaction and
intermediate coupling. Large splitting is seen in a line identified
with Fe I at 4137 nm, showing multiple Stokes V components and an
unusual linear polarization. This line will be a sensitive probe of
quiet-Sun magnetic fields, with a magnetic sensitivity of 2.5 times
higher than that of the well-known 1565 nm Fe I line.
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Title: Coronal Science from the Citizen CATE Experiment
Authors: Penn, Matthew J.; Pierce, Mike; Jensen, Logan; Baer, Bob;
Kovac, Sarah; Gelderman, Richard; Hare, Honor; Walter, Don; McKay,
Myles
2016shin.confE.154P Altcode:
The 2017 August total solar eclipse path crosses the USA from Oregon
to South Carolina, and the path is accessible at countless points. At
any single location totality lasts about 2 minutes, but the lunar
shadow takes 90 minutes to traverse the continent. With a collection
of 60 identical telescopes at 50 mile intervals, the Citizen CATE
Experiment will collect white images of the solar corona from 1 to
2 solar radii with 1500km resolution for a period of 90 minutes. <P
/>This unique data set probes spatial and temporal domains impossible
to observe from the ground or space. Assuming a typical solar minimum
corona, our science will focus on the dynamics of polar plumes and
the prominence-coronal interface. Polar plumes are thought to host
periodic or quasi-periodic density enhancements moving radially
outward; current work suggests 3-15% density enhancements moving at
60-210 km/sec with periods from 7-15 minutes. Rayleigh-Taylor plasma
instabilities observed in prominences at 2250km size scales with upward
velocities of 20 km/sec are thought to form larger dynamic structures
in the hot coronal plasma after leaving the prominence. The CATE data,
with transverse velocity sensitivities of 1 to 145 km/sec during the 90
minute duration will be used to tightly constrain both of these solar
phenomena. If the corona shows eruptive activity during the eclipse,
the CATE data can provide unique and stunning measurements of CMEs,
active region loop oscillations or even coronal inflows. <P />We will
review results from CATE tests from the Faroe Islands in 2015 and
from Indonesia in 2016, and provide a current status of CATE for the
2017 eclipse. The education and public outreach impact of this event,
which may be directly viewed by 20 million and seen on TV and internet
by more than 100 million will also be discussed.
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Title: Student artistry sparks eclipse excitement on Maui: NSO/DKIST
EPO for the 2016 Partial Solar Eclipse
Authors: Schad, Thomas A.; Penn, Matthew J.; Armstrong, James
2016SPD....47.0501S Altcode:
Local creativity and artistry is a powerful resource that enhances
education programs and helps us generate excitement for science
within our communities. In celebration of the 2016 Solar Eclipse,
the National Solar Observatory (NSO) and its Daniel K Inouye Solar
Telescope (DKIST) project were pleased to engage with students across
Maui County, Hawai`i, via the 2016 Maui Eclipse Art Contest. With
the help of the Maui Economic Development Board and the University
of Hawai'is Institute for Astronomy, we solicited art entries from
all K-12 schools in Maui County approximately 6 months prior to the
eclipse. Along with divisional prizes, a grand prize was selected
by a panel of local judges, which was subsequently printed on 25,000
solar eclipse viewing glasses and distributed to all Maui students. We
found that the impact of a locally-sourced glasses design cannot be
understated. Overall, the success of this program relied upon reaching
out to individual teachers, supplying educational flyers to all schools,
and visiting classrooms. On the day of the eclipse, all of the art
entries were prominently displayed during a community eclipse viewing
event at Kalama Beach Park in Kihei, HI, that was co-hosted by NSO
and the Maui Science Center. This eclipse art contest was integral to
making local connections to help promote science education on Maui,
and we suggest that it could be adapted to the solar community's EPO
activities for the upcoming 2017 Great American Solar Eclipse.
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Title: Cross-Calibrating Sunspot Magnetic Field Strength Measurements
from the McMath-Pierce Solar Telescope and the Dunn Solar Telescope
Authors: Watson, Fraser T.; Beck, Christian; Penn, Matthew J.;
Tritschler, Alexandra; Pillet, Valentín Martinez; Livingston,
William C.
2015SoPh..290.3267W Altcode: 2015arXiv151107315W; 2015SoPh..tmp..158W
In this article we describe a recent effort to cross-calibrate data
from an infrared detector at the McMath-Pierce Solar Telescope and
the Facility InfraRed Spectropolarimeter (FIRS) at the Dunn Solar
Telescope. A synoptic observation program at the McMath-Pierce has
measured umbral magnetic field strengths since 1998, and this data set
has recently been compared with umbral magnetic field observations from
SOHO/MDI and SDO/HMI. To further improve on the data from McMath-Pierce,
we compared the data with measurements taken at the Dunn Solar Telescope
with far greater spectral resolution than has been possible with
space instrumentation. To minimise potential disruption to the study,
concurrent umbral measurements were made so that the relationship
between the two datasets can be most accurately characterised. We find
that there is a strong agreement between the umbral magnetic field
strengths recorded by each instrument, and we reduced the FIRS data
in two different ways to successfully test this correlation further.
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Title: He I Vector Magnetic Field Maps of a Sunspot and Its
Superpenumbral Fine-Structure
Authors: Schad, T. A.; Penn, M. J.; Lin, H.; Tritschler, A.
2015SoPh..290.1607S Altcode: 2015arXiv150505567S; 2015SoPh..tmp...60S
Advanced inversions of high-resolution spectropolarimetric observations
of the He I triplet at 1083 nm are used to generate unique maps of
the chromospheric magnetic field vector across a sunspot and its
superpenumbral canopy. The observations were acquired by the Facility
Infrared Spectropolarimeter (FIRS) at the Dunn Solar Telescope (DST)
on 29 January 2012. Multiple atmospheric models are employed in the
inversions because superpenumbral Stokes profiles are dominated by
atomic-level polarization, while sunspot profiles are Zeeman-dominated,
but also exhibit signatures that might be induced by symmetry-breaking
effects of the radiation field incident on the chromospheric
material. We derive the equilibrium magnetic structure of a sunspot in
the chromosphere and furthermore show that the superpenumbral magnetic
field does not appear to be finely structured, unlike the observed
intensity structure. This suggests that fibrils are not concentrations
of magnetic flux, but are instead distinguished by individualized
thermalization. We also directly compare our inverted values with a
current-free extrapolation of the chromospheric field. With improved
measurements in the future, the average shear angle between the inferred
magnetic field and the potential field may offer a means to quantify
the non-potentiality of the chromospheric magnetic field to study the
onset of explosive solar phenomena.
---------------------------------------------------------
Title: Citizen CATE Experiment: Prototype Testing and Plans
Authors: Penn, Matthew; Baer, Bob; Isberner, Fred
2015SASS...34...63P Altcode:
An off-the-shelf small refracting telescope and digital imaging system
was purchased and tested for application to a citizen science experiment
to be run during the 2017 total solar eclipse. Ease of set-up, imaging
ability, and sensitivity tests were done, and then the telescope was
shipped to take data at the 2015 total solar eclipse from the Faroe
Islands. Details of the equipment, results from the tests, and plans
for future eclipses are discussed.
---------------------------------------------------------
Title: New Vector Spectropolarimetry of Sunspots near 4000nm
Authors: Penn, Matthew J.; Coulter, Roy; Goode, Philip R.
2014AAS...22411201P Altcode:
Magnetic sensitivity of spectral lines increases as the product of the
wavelength and the Lande g-factor. While the most magnetically sensitive
spectral line known is the Mg I 12318nm line, and observations are often
made near 1600nm, little work has been done using solar spectral lines
near 4000nmWe report on new solar spectropolarimetric observations at
these wavelengths, made at the NSO McMath-Pierce facility with the NAC
and at the NJIT New Solar Telescope using CYRA. Several photospheric
absorption lines have been used to map a sunspot magnetic field,
and molecular line Zeeman splitting has also been observed. Several
"negative-g" molecular lines are seen, and an atomic line shows
unusual profiles.
---------------------------------------------------------
Title: A Spectro-polarimetric Analysis of Sunspot Umbrae
Authors: Watson, Fraser; Tritschler, Alexandra; Penn, Matthew J.;
Beck, Christian; Livingston, William; Martinez Pillet, Valentin
2014AAS...22411202W Altcode:
The recent quiet solar cycle has invited new questions as to
the nature of the solar magnetic field and how it changes over
time. To investigate this, we use the National Solar Observatory’s
McMath-Pierce Solar Telescope Facility (McMP) and Dunn Solar Telescope
(DST) to compare measurements of sunspots from five active regions
observed in 2013. Both BABO at the McMP and FIRS at the DST were
used to provide spectra of the Fe 1564.8nm line, which is affected
by the presence of magnetic fields. The magnetic field is derived
from Zeeman splitting in Stokes-I by BABO, and by inversion of the
Stokes parameters from FIRS data allowing for comparisons of sunspot
properties between the two instruments.. We present the first results
from this study including the magnetic fields in sunspot umbrae from
five active regions measured simultaneously by BABO and FIRS.
---------------------------------------------------------
Title: A Multi-instrument Analysis of Sunspot Umbrae
Authors: Watson, F. T.; Penn, M. J.; Livingston, W.
2014ApJ...787...22W Altcode: 2015arXiv151107300W
The recent solar minimum and rise phase of solar cycle 24 have been
unlike any period since the early 1900s. This article examines some
of the properties of sunspot umbrae over the last 17 yr with three
different instruments on the ground and in space: MDI, HMI and BABO. The
distribution of magnetic fields and their evolution over time is shown
and reveals that the field distribution in cycle 24 is fundamentally
different from that in cycle 23. The annual average umbral magnetic
field is then examined for the 17 yr observation period and shows a
small decrease of 375 G in sunspot magnetic fields over the period
1996-2013, but the mean intensity of sunspot umbrae does not vary
significantly over this time. A possible issue with sample sizes in a
previous study is then explored to explain disagreements in data from
two of the source instruments. All three instruments show that the
relationship between umbral magnetic fields and umbral intensity agrees
with past studies in that the umbral intensity decreases as the field
strength increases. This apparent contradiction can be explained by the
range of magnetic field values measured for a given umbral intensity
being larger than the measured 375 G change in umbral field strength
over time.
---------------------------------------------------------
Title: Infrared Solar Physics
Authors: Penn, Matthew J.
2014LRSP...11....2P Altcode:
The infrared solar spectrum contains a wealth of physical data about
our Sun, and is explored using modern detectors and technology with
new ground-based solar telescopes. The scientific motivation behind
exploring these wavelengths is presented, along with a brief look
at the rich history of observations here. Several avenues of solar
physics research exploiting and benefiting from observations at infrared
wavelengths from roughly 1000 nm to 12 400 nm are discussed, and the
instrument and detector technology driving this research is briefly
summarized. Finally, goals for future work at infrared wavelengths
are presented in conjunction with ground and space-based observations.
---------------------------------------------------------
Title: A Systematic Look At Sunspots From Space: 1996 - 2013
Authors: Watson, Fraser; Penn, M. J.; Livingston, W.
2013SPD....4420401W Altcode:
Space based measurements of sunspots are still relatively new when
compared with the long visual record that is available from ground based
observatories, but they can provide many advantages that ground based
measurements cannot. Sunspots are automatically detected from SOHO/MDI
and SDO/HMI continuum images using the Sunspot Tracking And Recognition
Algorithm (STARA). A self consistent sunspot catalogue is created using
the same criteria for detecting sunspots throughout time, eliminating
effects seen by ground observatories such as changing observers or the
effect of an observers eyesight as they age. This catalogue is then
analysed to determine how sunspots evolve and what their population
is in a number of physical parameters, which is of great importance
for simulations of magnetic flux emergence and the solar dynamo. In
particular, the change in sunspot parameters between solar cycles 23
and 24 is of great interest as the cycles appear vastly different in
activity, and sunspots are a primary indicator of the activity of the
Sun. The catalogue is also freely available for use by the community.
---------------------------------------------------------
Title: Coronal science with the ATST
Authors: Penn, Matthew J.
2013SPD....4440101P Altcode:
The ATST project recently began construction on Haleakala, Maui. When
combined with the dark daytime sky conditions at the site, the low
scattered light primary mirror should allow ATST to make coronal
observations at infrared wavelengths. These data will address several
coronal science topics included in the ATST Science Requirements
Document. I will review the early work done by the ATST Coronal
Science Working Group, including these coronal science use cases
and the expected background-limited measurement errors. In summary,
the Working Group found that given good sky conditions the 1-sigma
measurement errors in a 40 millionths brightness corona were 0.04
millionths for intensity, 9 x 10^4 cm^-3 for electron density, 37 m
s^-1 for velocity and 33 Gauss for the magnetic field as measured in a
1 arcsecond square pixel with a 1 second exposure using the infrared
coronal emission lines at 1075nm. These measurement errors increase
as the telescope or sky backgrounds increase. Finally I will update
these error estimates from the latest telescope models, and discuss
recent coronal science topics.
---------------------------------------------------------
Title: Transit Observations of Venus's Atmosphere in 2012 from
Terrestrial and Space Telescopes as Exoplanet Analogs
Authors: Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.;
Penn, M. J.; Jaeggli, S. A.; Galayda, E.; Reardon, K. P.; Widemann,
T.; Tanga, P.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson, P. D.;
Dantowitz, R.
2013AAS...22221701P Altcode:
We extensively observed the 8 June 2012 transit of Venus from several
sites on Earth; we provide this interim status report about this and
about two subsequent ToVs observed from space. From Haleakala Obs., we
observed the entire June transit over almost 7 h with a coronagraph of
the Venus Twilight Experiment B filter) and with a RED Epic camera to
compare with simultaneous data from ESA's Venus Express, to study the
Cytherean mesosphere; from Kitt Peak, we have near-IR spectropolarimetry
at 1.6 µm from the aureole and during the disk crossing that compare
well with carbon dioxide spectral models; from Sac Peak/IBIS we have
high-resolution imaging of the Cytherean aureole for 22 min, starting
even before 1st contact; from Big Bear, we have high-resolution imaging
of Venus's atmosphere and the black-drop effect through 2nd contact;
and we had 8 other coronagraphs around the world. For the Sept 21 ToV
as seen from Jupiter, we had 14 orbits of HST to use Jupiter's clouds
as a reflecting surface to search for an 0.01% diminution in light and a
differential drop that would result from Venus's atmosphere by observing
in both IR/UV, for which we have 170 HST exposures. As of this writing,
preliminary data reduction indicates that variations in Jovian clouds
and the two periods of Jupiter's rotation will be too great to allow
extraction of the transit signal. For the December 20 ToV as seen from
Saturn, we had 22 hours of observing time with VIMS on Cassini, for
which we are looking for a signal of the 10-hr transit in total solar
irradiance and of Venus's atmosphere in IR as an exoplanet-transit
analog. Our Maui & Sac Peak expedition was sponsored by National
Geographic Society's Committee for Research and Exploration; HST data
reduction by NASA: HST-GO-13067. Some of the funds for the carbon
dioxide filter for Sac Peak provided by NASA through AAS's Small
Research Grant Program. We thank Rob Ratkowski of Haleakala Amateur
Astronomers; Rob Lucas, Aram Friedman, Eric Pilger, Stan Truitt,
and Steve Bisque/Software Bisque for Haleakala support/operations;
Vasyl Yurchyshyn and Joseph Gangestad '06 of The Aerospace Corp. at
Big Bear Solar Obs; LMSAL and Hinode science/operations team.
---------------------------------------------------------
Title: He I Vector Magnetometry of Field-aligned Superpenumbral
Fibrils
Authors: Schad, T. A.; Penn, M. J.; Lin, H.
2013ApJ...768..111S Altcode: 2013arXiv1303.4463S
Atomic-level polarization and Zeeman effect diagnostics in the neutral
helium triplet at 10830 Å in principle allow full vector magnetometry
of fine-scaled chromospheric fibrils. We present high-resolution
spectropolarimetric observations of superpenumbral fibrils in the
He I triplet with sufficient polarimetric sensitivity to infer
their full magnetic field geometry. He I observations from the
Facility Infrared Spectropolarimeter are paired with high-resolution
observations of the Hα 6563 Å and Ca II 8542 Å spectral lines from
the Interferometric Bidimensional Spectrometer from the Dunn Solar
Telescope in New Mexico. Linear and circular polarization signatures
in the He I triplet are measured and described, as well as analyzed
with the advanced inversion capability of the "Hanle and Zeeman Light"
modeling code. Our analysis provides direct evidence for the often
assumed field alignment of fibril structures. The projected angle of
the fibrils and the inferred magnetic field geometry align within an
error of ±10°. We describe changes in the inclination angle of these
features that reflect their connectivity with the photospheric magnetic
field. Evidence for an accelerated flow (~40 m s<SUP>-2</SUP>) along
an individual fibril anchored at its endpoints in the strong sunspot
and weaker plage in part supports the magnetic siphon flow mechanism's
role in the inverse Evershed effect. However, the connectivity of the
outer endpoint of many of the fibrils cannot be established.
---------------------------------------------------------
Title: Solar Spectra Fe 1564.8 nm Line and a Least Squares Analysis
Authors: Gottlieb, Amy; Penn, M.
2013AAS...22144501G Altcode:
Observations from the NSO McMath-Pierce solar facility of sunspot
spectra scans using the Fe I 1564.8 nm line have been re-examined. This
data has shown a long-term trend with decreasing magnetic field
strength and increasing temperature as discussed by Livingston, Penn
and Svalgaard (2012). We recompute the Zeeman splitting, line depth,
line width and Doppler shift in this line from about 200 spectra
from the 1998-2002 data using a multi-Gaussian least-squares fitting
technique. We find a direct correlation with the original values
determined by Livingston but with an offset of about 50 Gauss,
caused by a different spectral dispersion in the data than used in
the original work.
---------------------------------------------------------
Title: He I Spectropolarimetry with FIRS: Towards Vector Magnetometry
of Chromospheric Fibrils Plus New Diagnostics of Coronal Rain
Authors: Schad, T. A.; Penn, M. J.; Lin, H.; Tritschler, A.
2012ASPC..463...25S Altcode:
At the Dunn Solar Telescope, the Interferometric Bidimensional
Spectrometer (IBIS) can measure the full Stokes vector of the Ca II
854.2 nm spectral line while the Facility Infrared Spectropolarimeter
(FIRS) measures the Stokes vector of the He I triplet at 1083
nm. We analyze the He I triplet observed in two widely different
features above NOAA AR 11295 on 19 September 2011 - thin (< 1″)
chromospheric fibrils and a large-scale loop hosting a high-velocity
coronal rain event. These two features are shown to first demonstrate
the diagnostic potential of the He I triplet for magnetic fields in the
chromosphere/transition region and second to stress the need to pair
large-aperture facilities with flexible instrumentation. Inversions of
the He I triplet near the penumbral boundary return azimuthal directions
of the magnetic field aligned with fine-scale fibrils observed in the
line core of Ca II. The coronal rain event shows Doppler velocities
up to 195 km s<SUP>-1</SUP>, among the largest reported. We observe
measurable polarization within the raining material, which may be a
good magnetic diagnostic of chromospheric-like material higher in the
corona within condensating loops.
---------------------------------------------------------
Title: Decreasing Sunspot Magnetic Fields Explain Unique 10.7 cm
Radio Flux
Authors: Livingston, W.; Penn, M. J.; Svalgaard, L.
2012ApJ...757L...8L Altcode:
Infrared spectral observations of sunspots from 1998 to 2011 have shown
that on average sunspots changed, the magnetic fields weakened, and the
temperatures rose. The data also show that sunspots or dark pores can
only form at the solar surface if the magnetic field strength exceeds
about 1500 G. Sunspots appear at the solar surface with a variety of
field strengths, and during the period from 1998 to 2002 a histogram of
the sunspot magnetic fields shows a normal distribution with a mean of
2436 ± 26 G and a width of 323 ± 20 G. During this observing period
the mean of the magnetic field distribution decreased by 46 ± 6 G
per year, and we assume that as the 1500 G threshold was approached,
magnetic fields appeared at the solar surface which could not form dark
sunspots or pores. With this assumption we propose a quantity called
the sunspot formation fraction and give an analytical form derived
from the magnetic field distribution. We show that this fraction can
quantitatively explain the changing relationship between sunspot number
and solar radio flux measured at 10.7 cm wavelengths.
---------------------------------------------------------
Title: Multi-wavelength Spectropolarimetry Of A Sunspot Superpenumbra
With Firs And Ibis
Authors: Schad, Thomas A.; Tritschler, A.; Penn, M. J.
2012AAS...22020302S Altcode:
Extending nearly radially from magnetic field concentrations like
sunspot umbrae or pores, threadlike fibrils observed in the chromosphere
and transition region host a variety of dynamic behavior and have long
been considered local tracers for the magnetic field. Morphologically,
fibrils are similar to spicules seen on the limb. The connectivity
of fibrils outside of the magnetic field concentrations with the
photosphere and/or corona is not well understood, and probing the
magnetic field in these features remains challenging. In this
contribution we describe multi-wavelength spectropolarimetric
observations from the Dunn Solar Telescope in New Mexico using the
Facility Infrared Spectropolarimeter (FIRS) and the Interferometric
BiDimensional Spectropolarimeter (IBIS). FIRS performs high resolution
slit spectropolarimetry in the He I triplet at 1083 nm, which is a
promising diagnostic of chromospheric vector fields. Significant
progress has been made to boost the accuracy and sensitivity of
these measurements. Here we present measurements of an active region
sunspot at a spatial resolution of 0.3 arcsec and an RMS noise in
Stokes Q,U,V spectra down to 0.0003 in units of the local continuum
(SNR > 3300). We perform full inversions of these spectra taking
into account both Zeeman and Hanle effects. Initial results lend
support for field-aligned fibrils near the penumbral boundary of a
sunspot. Jointly with the FIRS observations, we use IBIS to observe the
Stokes vectors of Ca II 854.2 nm and Fe I 617.3 nm and the intensity
spectrum of H-alpha 656.3 nm. As a spectral imaging instrument, IBIS
rapidly scans through the three spectral lines over a 45” by 95” FOV
at an overall cadence of 50 seconds, allowing a much better description
the dynamics of fibrils observed by both FIRS and IBIS.
---------------------------------------------------------
Title: Decreasing Sunspot Magnetic Fields Explain Unique 10.7cm
Radio Flux
Authors: Penn, Matthew J.; Livingston, W.; Svalgaard, L.
2012AAS...22011004P Altcode:
Infrared spectral observations of sunspots from 1998-2011 have shown
that on average sunspots changed; the magnetic fields weakened and
the temperatures rose. The data also show that sunspots or dark pores
can only form at the solar surface only if the magnetic field strength
exceeds 1500 Gauss. Sunspots appear at the solar surface with a variety
of field strengths, and during the period from 1998-2002 a histogram
of the sunspot magnetic fields shows a normal distribution with a mean
near 2400 Gauss and a width of about 340 Gauss. During this observing
period the mean of the magnetic field distribution decreased by about
64 Gauss per year, and we assume that as the 1500 Gauss threshold
was approached, magnetic fields appeared at the solar surface which
could not form dark sunspots or pores With this assumption we propose
a quantity called the sunspot formation fraction and give an analytical
form derived from the magnetic field distribution. We show this fraction
can quantitatively explain the changing elationship between sunspot
number and solar radio flux measured at 10.7cm wavelengths.
---------------------------------------------------------
Title: Coronal Rain Observed On-disk with He I Spectropolarimetry
from DST/FIRS
Authors: Schad, Thomas A.; Penn, M. J.; Pietarila, A.
2012AAS...22031005S Altcode:
Coronal rain refers to cool, dense blobs of plasma that presumably
condense near the apex of hot coronal loops and then "rain" down upon
the chromosphere traveling along curved loop-like paths. Considered
to be the result of a thermal instability known as "catastrophic
cooling", coronal rain places constraints on heating mechanisms for
coronal loops. Nearly all observational studies of coronal rain,
however, have been limited to the solar limb where cooler material
within hot coronal loops is more readily identified. Here, we report
observations of what we interpret to be the on-disk counterpart of
coronal rain. Scanned spectropolarimetric observations in the He I
triplet (1083 nm) from the Facility Infrared Spectropolarimeter (FIRS)
reveal highly-redshifted material displaying an acceleration along
curved trajectories terminating within a large sunspot (located at
N17W21). Line-of-sight velocities in the He I triplet peak near 190
km/s, which can be consider high in relation to most coronal rain
observations. This is also the largest redshift ever reported in the
He I triplet. These curved loops correspond to an overarching loop
structure seen in SDO/AIA anchored at its ends by a large sunspot and
a group of pores. The loops observed with SDO/AIA display significant
cooling as dark (EUV absorptive) blobs begin to form near the loop
apex and then traverse along the same trajectories observed in the He
I FIRS observations. Although the EUVI instrument of STEREO-A/SECCHI
has a reduced temporal resolution compared to SDO/AIA, we are able
to confidently match rain features in both spacecraft and thus
stereoscopically reconstruct the three-dimensional trajectory to
confirm the material is raining upon the solar surface.
---------------------------------------------------------
Title: Sunspot Dynamics as seen with CO 4666nm Spectroscopy
Authors: Penn, Matthew J.; Schad, T.
2012AAS...22020610P Altcode:
High resolution adaptive-optics corrected spectroscopy of sunspots using
strong CO absorption lines at 4666nm was performed at the McMath-Pierce
Solar Telescope using the NSO Array Camera. Active region NOAA 11158
was observed after the X-class flare on 17 Feb 2011. Several hours of
rapid cadence scans reveal changes in umbral bright points, Evershed
flows, flows along a sheer zone and penumbral fibrils as seen with the
cool CO lines. Solar oscillations are studied, and the chromospheric
structure associated with the regions of CO absorption are examined
using 854.2nm Ca spectroscopy.
---------------------------------------------------------
Title: Long-term evolution of sunspot magnetic fields
Authors: Penn, Matthew J.; Livingston, William
2011IAUS..273..126P Altcode: 2010arXiv1009.0784P
Independent of the normal solar cycle, a decrease in the sunspot
magnetic field strength has been observed using the Zeeman-split
1564.8nm Fe I spectral line at the NSO Kitt Peak McMath-Pierce
telescope. Corresponding changes in sunspot brightness and the strength
of molecular absorption lines were also seen. This trend was seen
to continue in observations of the first sunspots of the new solar
Cycle 24, and extrapolating a linear fit to this trend would lead to
only half the number of spots in Cycle 24 compared to Cycle 23, and
imply virtually no sunspots in Cycle 25. <P />We examined synoptic
observations from the NSO Kitt Peak Vacuum Telescope and initially
(with 4000 spots) found a change in sunspot brightness which roughly
agreed with the infrared observations. A more detailed examination
(with 13,000 spots) of both spot brightness and line-of-sight magnetic
flux reveals that the relationship of the sunspot magnetic fields with
spot brightness and size remain constant during the solar cycle. There
are only small temporal variations in the spot brightness, size, and
line-of-sight flux seen in this larger sample. Because of the apparent
disagreement between the two data sets, we discuss how the infrared
spectral line provides a uniquely direct measurement of the magnetic
fields in sunspots.
---------------------------------------------------------
Title: Probing the Solar Atmosphere Using Oscillations of Infrared
CO Spectral Lines
Authors: Penn, M. J.; Schad, T.; Cox, E.
2011ApJ...734...47P Altcode: 2010arXiv1012.2371P
Oscillations were observed across the whole solar disk using the Doppler
shift and line center intensity of spectral lines from the CO molecule
near 4666 nm with the National Solar Observatory's McMath/Pierce
solar telescope. Power, coherence, and phase spectra were examined,
and diagnostic diagrams reveal power ridges at the solar global mode
frequencies to show that these oscillations are solar p-modes. The
phase was used to determine the height of formation of the CO lines by
comparison with the IR continuum intensity phase shifts as measured in
Kopp et al. we find that the CO line formation height varies from 425
km < z < 560 km as we move from disk center toward the solar limb
1.0 > μ > 0.5. The velocity power spectra show that while the
sum of the background and p-mode power increases with height in the
solar atmosphere as seen in previous work, the power in the p-modes
only (background subtracted) decreases with height. The CO line center
intensity weakens in regions of stronger magnetic fields, as does the
p-mode oscillation power. Across most of the solar surface the phase
shift is larger than the expected value of 90° for an adiabatic
atmosphere. We fit the phase spectra at different disk positions
with a simple atmospheric model to determine that the acoustic cutoff
frequency is about 4.5 mHz with only small variations, but that the
thermal relaxation frequency drops significantly from 2.7 to 0 mHz at
these heights in the solar atmosphere.
---------------------------------------------------------
Title: A Decade of Diminishing Sunspot Vigor
Authors: Livingston, W. C.; Penn, M.; Svalgard, L.
2011SPD....42.1721L Altcode: 2011BAAS..43S.1721L
<SUP>1</SUP>A Decade of Diminishing Sunspot Vigor <P />William
Livingston<SUP>1</SUP> <P />Matt Penn<SUP>1</SUP> <P />Leif
Svalgard<SUP>2</SUP> <P />Sunspots are small dark areas on the solar
disk where internal magnetism, 1500 to 3500 Gauss, has been buoyed to
the surface. (Spot life times are the order of one day to a couple of
weeks or more. They are thought to be dark because convection inhibits
the outward transport of energy there). Their "vigor” can be described
by spot area, spot brightness intensity, and magnetic field. From 2001
to 2011 we have measured field strength and brightness at the darkest
position in umbrae of 1750 spots using the Zeeman splitting of the
Fe 1564.8 nm line. Only one observation per spot per day is carried
out during our monthly telescope time of 3-4 days average. Over this
interval the temporal mean magnetic field has declined about 500 Gauss
and mean spot intensity has risen about 20%. We do not understand the
physical mechanism behind these changes or the effect, if any, it will
have on the Earth environment. <P />1. <P />wcl@noao.edu</u>
mpenn@noao.edu <P />2. <P />leif@leif.org
---------------------------------------------------------
Title: High-Resolution He I Spectropolarimetry of Chromospheric
Fibrils
Authors: Schad, Thomas A.; Penn, M. J.
2011SPD....42.0305S Altcode: 2011BAAS..43S.0305S
Of spectral diagnostics for the magnetic field in the solar
chromosphere, the He I triplet at 1083 nm offers a comparatively
simple means to determine both the magnitude and direction of the field
vector. The triplet forms over a narrow range of heights when compared
to strong optical lines, and recently the mechanisms that influence its
polarization have been well characterized, thus allowing inversions of
the magnetic field from observed Stokes profiles. We discuss recent work
with the Facility Infrared Spectropolarimeter (FIRS) at the Dunn Solar
Telescope (DST), New Mexico, USA to measure and infer the magnetic
field vector of chromospheric fibrils. FIRS is designed to perform
fast diffraction-limited dual-beam spectropolarimetry simultaneously
at visible and infrared wavelengths through the use of multiple slits
and narrowband filters. It can be operated in congress with the High
Order Adaptive Optics (HOAO) system of the DST as well as with the
Interferometric BiDimensional Spectropolarimeter (IBIS). Here we present
high-resolution FIRS observations of chromospheric fibrils which employ
the HOAO system under great seeing. We calibrate these observations
for the full effect of the FIRS-DST combined analysis system on the
Stokes vector which allow us to define the observed Stokes geometry
with respect to solar coordinates. Full inversions of our measurements
incorporating the effects of atomic polarization, the Hanle effect, and
the Zeeman effect will be presented showing support for chromospheric
fibrils that are aligned with the magnetic field direction.
---------------------------------------------------------
Title: Probing the Solar Atmosphere Using Oscillations of Infrared
CO Spectral Lines
Authors: Penn, Matthew J.; Schad, T.; Cox, E.
2011SPD....42.1702P Altcode: 2011BAAS..43S.1702P
Oscillations were observed across the whole solar disk using the Doppler
shift and line center intensity of spectral lines from the CO molecule
near 4666 nm with the National Solar Observatory's McMath/Pierce
solar telescope. Power, coherence, and phase spectra were examined,
and diagnostic diagrams reveal power ridges at the solar global mode
frequencies to show that these oscillations are solar p-modes. The
phase was used to determine the height of formation of the CO lines by
comparison with the IR continuum intensity phase shifts as measured in
Kopp et al., 1992; we find the CO line formation height varies from
425 < z < 560 km as we move from disk center towards the solar
limb 1.0 > mu > 0.5. The velocity power spectra show that while
the sum of the background and p-mode power increases with height in the
solar atmosphere as seen in previous work, the power in the p-modes only
(background subtracted) decreases with height. The CO line depth weakens
in regions of stronger magnetic fields, as does the p-mode oscillation
power. Across most of the solar surface the phase shift is larger than
the expected value of 90 degrees for an adiabatic atmosphere. We fit
the phase spectra at different disk positions with a simple atmospheric
model to determine that the acoustic cutoff frequency is about 4.5 mHz
with only small variations, but that the thermal relaxation frequency
drops significantly from 2.7 to 0 mHz at these heights in the solar
atmosphere.
---------------------------------------------------------
Title: Spectropolarimetry of Chromospheric Magnetic and Velocity
Structure Above Active Regions
Authors: Schad, T. A.; Jaeggli, S. A.; Lin, H.; Penn, M. J.
2011ASPC..437..483S Altcode: 2011arXiv1101.0631S
Active regions often host large-scale gas flows in the
chromosphere presumably directed along curved magnetic field
lines. Spectropolarimetric observations of these flows are critical to
understanding the nature and evolution of their anchoring magnetic
structure. We discuss recent work with the Facility Infrared
Spectropolarimeter (FIRS) located at the Dunn Solar Telescope in New
Mexico to achieve high-resolution imaging-spectropolarimetry of the Fe
I lines at 630 nm, the Si I line at 1082.7 nm, and the He I triplet at
1083 nm. We present maps of the photospheric and chromospheric magnetic
field vector above a sunspot as well as discuss characteristics of
surrounding chromospheric flow structures.
---------------------------------------------------------
Title: IR spectroscopy of COmosphere dynamics with the CO first
overtone band
Authors: Schad, T. A.; Penn, M. J.
2010AN....331..589S Altcode: 2010arXiv1008.5375S
We discuss observations of the weak first overtone (\Delta\nu=2) CO
absorption band near 2300 nm with the U.S. National Solar Observatory
Array Camera (NAC), a modern mid-infrared detector. This molecular
band provides a thermal diagnostic that forms lower in the atmosphere
than the stronger fundamental band near 4600 nm. The observed
center-to-limb increase in CO line width qualitatively agrees with
the proposed higher temperature shocks or faster plasma motions higher
in the COmosphere. The spatial extent of chromospheric shock waves is
currently at or below the diffraction limit of the available CO lines at
existing telescopes. Five minute period oscillations in line strength
and measured Doppler shifts are consistent with the p-mode excitation
of the photospheric gas. We also show recent efforts at direct imaging
at 4600 nm. We stress that future large-aperture solar telescopes must
be teamed with improved, dynamic mid-infrared instruments, like the NAC,
to capitalize on the features that motivate such facilities.
---------------------------------------------------------
Title: Structural Invariance of Sunspot Umbrae over the Solar Cycle:
1993 - 2004
Authors: Schad, T. A.; Penn, M. J.
2010SoPh..262...19S Altcode: 2010SoPh..tmp...22S; 2009arXiv0912.2370S
Measurements of maximum magnetic flux, minimum intensity, and size
are presented for 12 967 sunspot umbrae detected on the National
Aeronautics and Space Administration/National Solar Observatory
(NASA/NSO) spectromagnetograms between 1993 and 2004 to study
umbral structure and strength during the solar cycle. The umbrae
are selected using an automated thresholding technique. Measured
umbral intensities are first corrected for center-to-limb intensity
dependence. Log-normal fits to the observed size distribution confirm
that the size-spectrum shape does not vary with time. The intensity
- magnetic-flux relationship is found to be steady over the solar
cycle. The dependence of umbral size on the magnetic flux and minimum
intensity are also independent of the cycle phase and give linear and
quadratic relations, respectively. While the large sample size does show
a low-amplitude oscillation in the mean minimum intensity and maximum
magnetic flux correlated with the solar cycle, this can be explained
in terms of variations in the mean umbral size. These size variations,
however, are small and do not substantiate a meaningful change in the
size spectrum of the umbrae generated by the Sun. Thus, in contrast to
previous reports, the observations suggest the equilibrium structure,
as manifested by the invariant size-magnetic field relationship,
as well as the mean size (i.e., strength) of sunspot umbrae do not
significantly depend on the solar-cycle phase.
---------------------------------------------------------
Title: FIRS: a new instrument for photospheric and chromospheric
studies at the DST.
Authors: Jaeggli, S. A.; Lin, H.; Mickey, D. L.; Kuhn, J. R.; Hegwer,
S. L.; Rimmele, T. R.; Penn, M. J.
2010MmSAI..81..763J Altcode:
The simultaneous observation of select spectral lines at optical and
infrared wavelengths allows for the determination of the magnetic
field at several photospheric and chromospheric heights and thus
the 3D magnetic field gradient in the solar atmosphere. The Facility
Infrared Spectropolarimeter (FIRS) is a newly completed, multi-slit,
dual-beam spectropolarimeter installed at the Dunn Solar Telescope
(DST) at Sacramento Peak (NSO/SP). Separate optics and polarimeters
simultaneously observe two band-passes at visible and infrared
wavelengths with a choice of two modes: the Fe I 6302 Å and 15648 Å
lines in the photosphere; or the Fe I 6302 Å and He I 10830 Å line
in the photosphere and high chromosphere, respectively. FIRS can also
operate simultaneously with a white light camera, G-band imager, and
the Interferometric Bi-dimensional Spectrometer (IBIS) observing the
mid-chromospheric Ca II 8542 Å line. The instrument uses four parallel
slits to sample four slices of the solar surface simultaneously to
achieve fast, diffraction-limited precision imaging spectropolarimetry,
enabling the study of MHD phenomena with short dynamic time scales.
---------------------------------------------------------
Title: Are Sunspots Different During This Solar Minimum?
Authors: Livingston, W.; Penn, M.
2009EOSTr..90..257L Altcode:
For hundreds of years, humans have observed that the Sun has displayed
activity where the number of sunspots increases and then decreases
at approximately 11-year intervals. Sunspots are dark regions on the
solar disk with magnetic field strengths greater than 1500 gauss (see
Figure 1), and the 11-year sunspot cycle is actually a 22-year cycle in
the solar magnetic field, with sunspots showing the same hemispheric
magnetic polarity on alternate 11-year cycles. The last solar maximum
occurred in 2001, and the magnetically active sunspots at that time
produced powerful flares causing large geomagnetic disturbances and
disrupting some space-based technology. But something is unusual
about the current sunspot cycle. The current solar minimum has been
unusually long, and with more than 670 days without sunspots through
June 2009, the number of spotless days has not been equaled since 1933
(see http://users.telenet.be/j.janssens/Spotless//Spotless.html). The
solar wind is reported to be in a uniquely low energy state since
space measurements began nearly 40 years ago [Fisk and Zhao, 2009].
---------------------------------------------------------
Title: Evershed Outflow During Solar Cycle 23
Authors: Penn, Matthew J.; Schad, T.
2009SPD....40.0907P Altcode:
We analyze several thousand Doppler observations of Evershed outflow
in sunspot penumbrae taken at the National Solar Observatory's Kitt
Peak Vacuum Telescope from 1993 to 2003. We compare the mean penumbral
flow vector components with properties of the sunspot, latitude of the
sunspot, and search for evolution of the components as a function of
time. We discuss how our findings relate to measurements of sunspot
magnetic helicity.
---------------------------------------------------------
Title: Near IR observations of Quiet Chromosphere
Authors: Prasad Choudhary, Debi; Deng, N.; Tejamoortula, U.; Penn,
M. J.
2009SPD....40.1005P Altcode:
We have carried out the observations of quiet solar limb during April
29 to May 1, 2008, March 9-13, 2009 using the vertical spectrograph
at the focal plane of McMath-Pierce telescope at Kitt Peak National
Observatory. The solar limb was mostly featureless during the
observations. The New Infrared Array (NAC) at the exit port of the
spectrograph has been used to record the limb spectrum at HeI 1083.0
nm, Hydrogen Paschen beta at 1281.8 nm and Brackett gamma 2165.5 nm
wavelength regions. The NAC is a 1024 x 1024 InSb Alladin III Detector
operating over 1-5 micron range with high density sampling at 0.018
arc second/pixel. The all-reflective optical train minimizes number
of surfaces and eliminates ghosts leading to low scatter, ghost-free
optics. The close-cycle cryogenic provides a stable cooling environment
over six hour period with an accuracy of about 0.01K leading to low
dark current. The low read out noise combined with low scattered light
and dark current makes NAC an ideal detector for making high quality
infrared spectral observations of solar limb. In this presentation,
we shall compare the line parameters of these lines around the solar
disk. <P />Acknowledgements: <P />This work is supported by NSF under
grant ATM 05-48952 and by NASA under grant NNX08AQ32G.
---------------------------------------------------------
Title: Dynamics of Quiet Solar Chromosphere at the Limb
Authors: Choudhary, D.; Tejomoortula, U.; Penn, M. J.
2008AGUFMSH23A1622C Altcode:
We have observed the solar limb using 1024 × 1024 InSb Near Infrared
Camera and Spectroheliograph at McMath-Pierce telescope during the
solar minimum period of April 29 to May 1, 2008. A 120 micron slit,
corresponding to 0.3 arc second was aligned perpendicular to the solar
limb for the observations. The slit spectrum with a resolution of
0.036 Å corresponding to about 05 to 1.0 km/s were obtained in the
wavelength regions of HeI 10830 Å, Hydogen Paschen α 12818 Å and
Hydrogen Brackett γ 21661 Å. Excellent seeing conditions and the use
of adaptive optics produced stable observing conditions during most
of the observations. We present the results of line width variation
as a function of chromospheric height around the solar limb.
---------------------------------------------------------
Title: A New Era in Solar Thermal-IR Astronomy: the NSO Array Camera
(NAC) on the McMath-Pierce Telescope
Authors: Ayres, T.; Penn, M.; Plymate, C.; Keller, C.
2008ESPM...12.2.74A Altcode:
The U.S. National Solar Observatory Array Camera (NAC) is a
cryogenically cooled 1Kx1K InSb “Aladdin" array that recently became
operational at the McMath-Pierce facility on Kitt Peak, a high dry site
in the southwest U.S. (Arizona). The new camera is similar to those
already incorporated into instruments on nighttime telescopes, and has
unprecedented sensitivity, low noise, and excellent cosmetics compared
with the Amber Engineering (AE) device it replaces. (The latter was
scavenged from a commercial surveillance camera in the 1990's: only
256X256 format, high noise, and annoying flatfield structure). The
NAC focal plane is maintained at 30 K by a mechanical closed-cycle
helium cooler, dispensing with the cumbersome pumped--solid-N2 40 K
system used previously with the AE camera. The NAC linearity has been
verified for exposures as short as 1 ms, although latency in the data
recording holds the maximum frame rate to about 8 Hz (in "streaming
mode"). The camera is run in tandem with the Infrared Adaptive
Optics (IRAO) system. Utilizing a 37-actuator deformable mirror, IRAO
can--under moderate seeing conditions--correct the telescope image to
the diffraction limit longward of 2.3 mu (if a suitable high contrast
target is available: the IR granulation has proven too bland to reliably
track). IRAO also provides fine control over the solar image for spatial
scanning in long-slit mode with the 14 m vertical "Main" spectrograph
(MS). A 1'X1' area scan, with 0.5" steps orthogonal to the slit
direction, requires less than half a minute, much shorter than p-mode
and granulation evolution time scales. A recent engineering test run,
in April 2008, utilized NAC/IRAO/MS to capture the fundamental (4.6 mu)
and first-overtone (2.3 mu) rovibrational bands of CO, including maps
of quiet regions, drift scans along the equatorial limbs (to measure
the off-limb molecular emissions), and imaging of a fortuitous small
sunspot pair, a final gasp, perhaps, of Cycle 23. Future work with
the NAC will emphasize pathfinding toward the next generation of IR
imaging spectrometers for the Advanced Technology Solar Telescope,
whose 4 m aperture finally will bring sorely needed high spatial
resolution to daytime infrared astronomy. In the meantime, the NAC
is available to qualified solar physicists from around the world to
conduct forefront research in the 1-5 mu region, on the venerable--but
infrared friendly--McMath-Pierce telescope.
---------------------------------------------------------
Title: The Facility IR Spectropolarimeter for the Dunn Solar Telescope
Authors: Jaeggli, S. A.; Lin, H.; Mickey, D. L.; Kuhn, J. R.; Hegwer,
S. L.; Rimmele, T. R.; Penn, M. J.
2008AGUSMSH31A..11J Altcode:
The Facility IR Spectropolarimeter(FIRS) is a multi-slit
spectropolarimeter designed for the Dunn Solar Telescope (DST) at the
National Solar Observatory on Sacramento Peak (NSO/SP) in New Mexico to
study magnetism on the solar surface. The instrument samples adjacent
slices of the solar surface using four parallel slits to achieve high
cadence, diffraction-limited, precision imaging-spectropolarimetry. Due
to the versatile, multi-armed design of the spectrograph, up to
four spectral lines at visible and infrared wavelengths, covering
four different heights in the solar atmosphere, can be observed
simultaneously. In this poster-paper we will describe the design,
capabilities, and performance of the instrument.
---------------------------------------------------------
Title: Solar Cycle Dependence of Umbral Magneto-Induced Line
Broadening
Authors: Schad, T. A.; Penn, M. J.
2008AGUSMSP41B..06S Altcode:
Studies of the solar cycle dependence of peak umbral magnetic field
strength have focused upon measurements of continuum intensity and
the Zeeman splitting of infrared spectral lines. Here we extend the
discussion into a measurement of effective line width using eleven years
of spectromagnetograms from the Kitt Peak Vacuum Telescope (KPVT). The
KPVT observed the 868.8 nm Fe I absorption line in opposing states of
circular polarization between 1992 and 2003, deriving full-disk images
of line-of-sight (LOS) velocity, LOS magnetic flux, continuum intensity,
equivalent line width, and central line depth. We determine an effective
spectral line width through a relation of the measured equivalent line
widths and central line depths. Developing a basic model of the Stokes
line profiles using the Seares formalism, we illustrate that a change in
the effective line width within the umbra as determined using the KPVT
data is consistent with the change in the Zeeman splitting. We discuss
the effect of observed distance from disk center, stray light, and the
unknown inclination angle of the magnetic field. Within individual
sunspots observed near disk center, the determined effective line
width decreases with distance from the umbral core consistent with the
studied magnetic field gradient. Measurements of different sunspots
show a clear dependence on umbral size consistent with previous studies
of the umbral magnetic field. Using this effective line width as a
diagnostic for magnetic field, we examine the dependence of maximum
magnetic field strength on the phase of the solar cycle. We present
a comprehensive statistical analysis using a sample size of over 3500
umbral measurements.
---------------------------------------------------------
Title: Near Infrared Observations of Solar Granulation
Authors: Penn, M.
2008AGUSMSP41B..01P Altcode:
The near infrared continuum provides a unique window for the study of
solar granulation. The opacity minimum at a wavelength of 1600nm allows
granulation to be imaged at a depth of roughly 50km below the optical
depth unity (500nm) level, and the continuum at 5000nm, formed by H-
free-free opacity, arises from a layer roughly 70 km above the optical
depth unity level. There are two challenges in observing granulation
in the infrared; image motion and distortion from the Earth's
atmosphere, and telescopic resolution at longer wavelengths. To meet
these challenges we present data from the National Solar Observatory
McMath-Pierce Main Telescope (currently the largest solar telescope with
a 1.6m aperture) using adaptive optics and post-processing techniques
to remove seeing effects.
---------------------------------------------------------
Title: Solar Cycle Changes in Sunspot Umbral Intensity
Authors: Penn, M. J.; MacDonald, R. K. D.
2007ApJ...662L.123P Altcode:
The minimum intensities of sunspot umbrae were measured from
1992 through 2003 using the National Solar Observatory Kitt Peak
Vacuum Telescope spectromagnetograph data. The resulting 3931 umbral
measurements reveal a solar cycle variation in the umbral intensity,
with umbrae appearing brighter on average at cycle minimum and darker
at cycle maximum. Recent studies of umbral intensity have been in
direct conflict with each other, showing decreasing, increasing, or
no umbral intensity trends. By providing a longer temporal baseline,
our new measurements uncover a solar cycle oscillation in umbral
intensity. From this new perspective we show how previous studies agree
with our work and with each other when the same phase of the solar
cycle is examined. Also in agreement with other investigators, the
solar cycle variation in the daily average umbral area, the lognormal
distribution of umbral area, and the near constancy of the mean umbral
radius during the solar cycle are seen in this data.
---------------------------------------------------------
Title: Further Investigations of the Umbral Intensity of Sunspots
Authors: MacDonald, Rachel; Penn, M. J.
2007AAS...210.9201M Altcode: 2007BAAS...39R.208M
In the summer of 2006 the minimum umbral intensity of sunspots was
studied for over 3000 sunspots observed by the Kitt Peak Vacuum
Telescope from November, 1992, to September, 2003. A trend was found
in the variation of the minimum intensity that was tied to the solar
cycle--minimum umbral intensity increased from solar maximum to
minimum, and decreased from solar minimum to maximum. These results
agreed with several previous works on the subject. In the fall of 2006
the minimum umbral intensity was investigated once more using sunspots
observed through the Michaelson Doppler Imager (MDI) instrument on the
Solar and Heliospheric Observatory (SOHO) satellite. The same analysis
software was used on the MDI data as on the KPVT data, studying over
4500 sunspots from June, 1996, to December, 2005. Results of this
analysis will be compared with the KPVT results, and with those of
previous works. <P />This work is carried out through the National Solar
Observatory Research Experiences for Undergraduate (REU) site program,
which is co-funded by the Department of Defense in partnership with
the National Science Foundation REU Program.
---------------------------------------------------------
Title: Recent Results From The NSO Array Camera
Authors: Plymate, Claude; Penn, M. J.
2007AAS...210.2409P Altcode: 2007BAAS...39..130P
The McMath-Pierce Solar Telescope (McMP) utilizes an all-reflecting
optical system of 1.6-meter aperture, still the largest among
solar telescopes. This unique optical configuration allows for
high spatial, spectral and temporal infrared mapping of the solar
surface. The National Solar Observatory (NSO) has invested in a robust
IR instrumentation development program at the McMP. Now available as a
facility instrument is a 1024<SUP>2</SUP> InSb array camera for use in
the 1 - 5 µm thermal infrared. Known as the NSO Array Camera (NAC),
it was designed to couple to the telescope's very high dispersion
spectrograph. The spectral imaging capability of the NAC is enhanced
with a low-order IR adaptive optics (IRAO) system designed to correct
seeing to the diffraction limit of the telescope under moderate seeing
conditions redward of 2.3 µm. The IRAO can scan the corrected image
across the spectrograph input slit allowing 2-D mapping of the solar
surface. Liquid crystal retardation modulators and polarizing optics
have been added to the spectrograph to enable the NAC to record IR
Stokes polarimetry data. Presented here are movies of solar granulation
at 2.2 µm obtained with the NAC/IRAO, Stokes polarimetric spectra of
the 1.56 µm g=3 Fe I absorption line, and sample observations of the
CO 4.6 µm absorption lines.
---------------------------------------------------------
Title: Observations of Solar Structures and Oscillations with Infrared
CO Absorption Lines
Authors: Penn, Matthew J.
2007AAS...21012003P Altcode: 2007BAAS...39..245P
Observations of several infrared absorption lines from the CO molecule
have been made with the NSO Array Camera at the McMath/Pierce Telescope
at Kitt Peak. The NAC provides cleaner slit spectra than previously
obtained with older camera systems, and we are able to fit the CO line
profiles to measure line depth, position and width. Spectroheliograms
are produced from these quantities,and the observations show the
well-known CO limb darkening, emission just above the continuum
limb, increasing line width at the limb, and decreased absorption
line strength near a hot, presumably magnetic feature. Time sequence
observations show solar oscillations in the line strength and central
wavelength and continuum brightness, and for the first time oscillations
are measured using the CO line width. Velocity maps in the CO lines near
the limb show steady horizontal flows in supergranule-like features.
---------------------------------------------------------
Title: Penumbral Moving Magnetic Features
Authors: Penn, M. J.; Jaeggli, S. A.; Henney, C. J.; Luszcz, S.;
Walton, S. R.
2006ASPC..358...31P Altcode:
Moving magnetic features are observed in the penumbrae of two sunspots
with time sequences of vector magnetic field measurements taken in
the infrared Fe I 1565 nm spectral line (g=3). These features move
with similar radial velocities as previously observed continuum and
G-band features, and confirm a short sequence of penumbral magnetic
observations in the visible. These features move with similar speeds
to the moving magnetic features seen outside sunspot penumbrae, and
in some cases they are seen to cross the penumbral boundary and move
across the sunspot moat. Magnetic and flow parameters are briefly
compared with predictions from the moving flux tube model.
---------------------------------------------------------
Title: Temporal Changes in Sunspot Umbral Magnetic Fields and
Temperatures
Authors: Penn, M. J.; Livingston, W.
2006ApJ...649L..45P Altcode:
We have observed high-resolution intensity spectra near the Fe I
1564.8 nm line at a single umbral point corresponding to the darkest
position in over 900 sunspots from 1998 through 2005. From these
data we determine that the maximum sunspot magnetic fields have been
decreasing at about 52 G yr<SUP>-1</SUP>. The same data set shows a
concurrent increase in the normalized umbral intensity from 0.60 to 0.75
(corresponding to a blackbody temperature rise from 5137 to 5719 K)
and a decrease of more than 50% in the molecular OH line strength. The
magnetic field and intensity changes observed over time in the sunspot
umbrae from different spots behave in the same way as the magnetic
field and intensity changes observed spatially across single sunspots.
---------------------------------------------------------
Title: NAC Observations of an X1.8 Flare
Authors: Penn, Matthew J.
2006SPD....37.0811P Altcode: 2006BAAS...38..232P
The NSO Array Camera (NAC) observed He 1083nm spectral line profiles in
the active region NOAA 10808 before, during and after the X1.8 flare
of 13 Sep 2005. The NAC observations were made at the McMath-Pierce
main telescope using the spectrograph and the IR grating. The spatial
field-of-view was limited to the umbra and immediately surrounding
penumbra, but the spectral coverage ranged from 1080 to 1085nm. Before
the flare regions of strong downflows (30 km/s) are seen; during the
flare very bright emission (2.5 times the continuum intensity) are seen
in line center in several kernels near the umbral/penumbral boundary;
and after the flare, narrow spatial structures are seen with broad
spectral absorption profiles showing downflows exceeding 100 km/s.
---------------------------------------------------------
Title: Site testing for the Advanced Technology Solar Telescope
Authors: Hill, F.; Beckers, J.; Brandt, P.; Briggs, J.; Brown, T.;
Brown, W.; Collados, M.; Denker, C.; Fletcher, S.; Hegwer, S.; Horst,
T.; Komsa, M.; Kuhn, J.; Lecinski, A.; Lin, H.; Oncley, S.; Penn,
M.; Radick, R.; Rimmele, T.; Socas-Navarro, H.; Streander, K.
2006SPIE.6267E..1TH Altcode: 2006SPIE.6267E..59H
The Advanced Solar Technology Telescope (ATST) is a 4-m solar telescope
being designed for high spatial, spectral and temporal resolution,
as well as IR and low-scattered light observations. The overall
limit of performance of the telescope is strongly influenced by the
qualities of the site at which it is located. Six sites were tested
with a seeing monitor and a sky brightness instrument for 1.5 to 2
years. The sites were Big Bear (California), Haleakala (Hawaii), La
Palma (Canary Islands, Spain), Panguitch Lake (Utah), Sacramento Peak
(New Mexico), and San Pedro Martir (Baja California, Mexico). In this
paper we will describe the methods and results of the site survey,
which chose Haleakala as the location of the ATST.
---------------------------------------------------------
Title: Large-scale Structures and their Role in Solar Activity
Authors: Sankarasubramanian, K.; Penn, M.; Pevtsov, A.
2005ASPC..346.....S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polarization in Mercury's Exosphere
Authors: Allen, J. E., Jr.; Penn, M. J.
2005ASPC..343..181A Altcode:
The linear polarization states of the sodium D-lines in the exosphere of
Mercury have been determined from high-resolution spectropolarimetric
images acquired with a polarization analysis package coupled to a
Fabry-Perot interferometer; the results were subsequently confirmed
using an equivalent polarization package with a high-resolution
spectrograph.
---------------------------------------------------------
Title: Solar Site Survey for the Advanced Technology Solar
Telescope. I. Analysis of the Seeing Data
Authors: Socas-Navarro, H.; Beckers, J.; Brandt, P.; Briggs, J.;
Brown, T.; Brown, W.; Collados, M.; Denker, C.; Fletcher, S.; Hegwer,
S.; Hill, F.; Horst, T.; Komsa, M.; Kuhn, J.; Lecinski, A.; Lin, H.;
Oncley, S.; Penn, M.; Rimmele, T.; Streander, K.
2005PASP..117.1296S Altcode: 2005astro.ph..8690S
The site survey for the Advanced Technology Solar Telescope concluded
recently after more than 2 years of data gathering and analysis. Six
locations, including lake, island, and continental sites, were
thoroughly probed for image quality and sky brightness. The present
paper describes the analysis methodology employed to determine the
height stratification of the atmospheric turbulence. This information
is crucial, because daytime seeing is often very different between the
actual telescope aperture (~30 m) and the ground. Two independent
inversion codes have been developed to simultaneously analyze
data from a scintillometer array and a solar differential image
monitor. We show here the results of applying them to a sample subset
of data from 2003 May that was used for testing. Both codes retrieve a
similar seeing stratification through the height range of interest. A
quantitative comparison between our analysis procedure and actual in
situ measurements confirms the validity of the inversions. The sample
data presented in this paper reveal a qualitatively different behavior
for the lake sites (dominated by high-altitude seeing) and the rest
(dominated by near-ground turbulence).
---------------------------------------------------------
Title: The ATST Site Survey
Authors: Hill, F.; Beckers, J.; Brandt, P.; Briggs, J. W.; Brown, T.;
Brown, W.; Collados, M.; Denker, C.; Fletcher, S.; Hegwer, S.; Horst,
T.; Komsa, M.; Kuhn, J.; Lecinski, A.; Lin, H.; Oncley, S.; Penn, M.;
Radick, R.; Rimmele, T.; Socas-Navarro, H.; Soltau, D.; Streander, K.
2005AGUSMSP34A..04H Altcode:
The Advanced Technology Solar Telescope (ATST) will be the world's
largest aperture solar telescope, and is being designed for high
resolution, IR, and coronal research. It must be located at a site that
maximizes the scientific return of this substantial investment. We
present the instrumentation, analysis and results of the ATST site
survey. Two instrumentation sets were deployed at each of six sites to
measure seeing as a function of height, and sky brightness as a function
of wavelength and off-limb position. Analysis software was developed
to estimate the structure function Cn2 as a function of height near
the ground, and the results were verified by comparison with in-situ
measurements. Additional software was developed to estimate the sky
brightness. The statistics of the conditions at the sites were corrected
for observing habits and the annualized hours of specific observing
conditions were estimated. These results were used to identify three
excellent sites suitable to host the ATST: Haleakala, Big Bear and La
Palma. Among them, Haleakala is proposed as the optimal location of
the ATST, La Palma and Big Bear being viable alternative sites.
---------------------------------------------------------
Title: Searching for Moving Magnetic Features at 1565 nm
Authors: Jaeggli, S. A.; Penn, M. J.; Henney, C. J.
2005AGUSMSP41B..01J Altcode:
Spectropolarimetric data of the active region 10663 was taken with
the CSUN-NSO IR camera and the McMath-Pierce telescope on August 26,
2004 from 16:35 to 21:02 UT. Utilizing the Zeeman split Fe I line near
1565 nm, the data is processed to remove instrumental polarization
and a Milne-Eddington inversion technique is applied. The results of
the inversion are used to examine the physical properties and radial
motions of moving magnetic features which appear to originate in the
sunspot penumbra.
---------------------------------------------------------
Title: Moving Magnetic Features Inside the Penumbra of NOAO 10008
Authors: Luszcz, S. H.; Penn, M. J.; Jaeggli, S. A.; Henney, C. J.
2005AGUSMSP11A..05L Altcode:
Over 30 years of observations and theories comprise the study of moving
magnetic features (MMFs). MMFs, which often occur in opposite polarity
pairs, migrate radially outward through the sunspot moat at speeds of
about 1 km~s-1. A sequence of sixteen scans of the active region NOAO
10008 were taken using the NSO-CSUN IR camera at the NSO McMath-Pierce
Solar Telescope on 24 June 2002 17:38-21:59. Using the Fe I absorption
line at 1564.8nm, magnetogram images and maps of the magnetic field
vector were produced, revealing magnetic features within the penumbra
that appear to move radially outward at similar velocities and azimuth
angles as those of MMFs in the moat. We use polar time slice images
to measure the radial velocities of both types of features. This
work is carried out through the National Solar Observatory Research
Experiences for Undergraduate (REU) site program, which is co-funded
by the Department of Defense in partnership with the National Science
Foundation REU Program.
---------------------------------------------------------
Title: The 1564.6nm CN Line in Sunspots
Authors: Penn, M. J.; Jaeggli, S. A.
2005AGUSMSP11A..02P Altcode:
The line strength of CN absorption has been observed to vary with
the continuum intensity within sunspots, and the Doppler shift of
the CN line at 1564.6nm has been shown to reveal fast Evershed flows
in the penumbra. We examine several sunspots observed from 2002-2005
using intensity spectroscopy and spectropolarimetry to determine the
line strength, plasma flow velocity, and the local magnetic field
configuration as functions of position in these sunspots.
---------------------------------------------------------
Title: Solar site testing for the Advanced Technology Solar Telescope
Authors: Hill, Frank; Beckers, Jacques; Brandt, Peter; Briggs, John;
Brown, Timothy; Brown, W.; Collados, Manuel; Denker, Carsten; Fletcher,
Steven; Hegwer, Steven; Horst, T.; Komsa, Mark; Kuhn, Jeff; Lecinski,
Alice; Lin, Haosheng; Oncley, Steve; Penn, Matthew; Rimmele, Thomas
R.; Socas-Navarro, Hector; Streander, Kim
2004SPIE.5489..122H Altcode:
The location of the Advanced Technology Solar Telescope (ATST) is a
critical factor in the overall performance of the telescope. We have
developed a set of instrumentation to measure daytime seeing, sky
brightness, cloud cover, water vapor, dust levels, and weather. The
instruments have been located at six sites for periods of one to two
years. Here we describe the sites and instrumentation, discuss the
data reduction, and present some preliminary results. We demonstrate
that it is possible to estimate seeing as a function of height near the
ground with an array of scintillometers, and that there is a distinct
qualitative difference in daytime seeing between sites with or without
a nearby lake.
---------------------------------------------------------
Title: The Advanced Technology Solar Telescope Site Survey Sky
Brightness Monitor
Authors: Lin, Haosheng; Penn, Matthew J.
2004PASP..116..652L Altcode:
The Advanced Technology Solar Telescope (ATST) will be a 4 m aperture
off-axis telescope with advanced high-resolution and low scattered
light capabilities for the observation of the solar photosphere and
corona. The site characteristics that are critical to the success of
the ATST coronal observations are the sky brightness, the precipitable
water vapor content, and the number and size distributions of the
dust particles. Therefore, part of the ATST site survey effort is
to obtain measurements of these atmospheric properties at all the
potential ATST sites. The ATST site survey Sky Brightness Monitor (SBM)
is a new instrument specifically developed for this task. The SBM is a
modified externally occulted coronagraph capable of imaging the solar
disk and sky simultaneously. The ability to image the Sun and the sky
simultaneously greatly simplifies the calibration of the sky-brightness
measurements. The SBM has a very simple optical configuration that makes
it a compact and low-maintenance instrument. The SBM is sensitive to sky
brightness below 1×10<SUP>-6</SUP> disk center intensity, with a field
of view extending from 4 to 8 R<SUB>solar</SUB>. It measures the solar
disk and sky brightness at three continuum bandpasses located at 450,
530, and 890 nm. A fourth bandpass is centered at the 940 nm water vapor
absorption band. With measurements of disk and sky brightness at these
four wavelengths, site characteristics such as extinctions, aerosol
content, and precipitable water vapor content can be derived. This
paper documents the design, specifications, calibration procedures,
and performance of the SBM.
---------------------------------------------------------
Title: Background-Induced Measurement Errors of the Coronal Intensity,
Density, Velocity, and Magnetic Field
Authors: Penn, M. J.; Lin, H.; Tomczyk, S.; Elmore, D.; Judge, P.
2004SoPh..222...61P Altcode:
The effect of a background signal on the signal-to-noise ratio is
discussed, with particular application to ground-based observations of
emission lines in the solar corona with the proposed Advanced Technology
Solar Telescope. The concepts of effective coronal aperture and
effective coronal integration time are introduced. Specific expressions
are developed for the 1σ measurement errors for coronal intensity,
coronal electron density, coronal velocity, and coronal magnetic field
measurements using emission lines and including a background.
---------------------------------------------------------
Title: Latest Results from the ATST Site Survey
Authors: Hill, F.; Collados, M.; Navarro, H.; Beckers, J.; Brandt,
P.; Briggs, J.; Brown, T.; Denker, C.; Hegwer, S.; Horst, T.; Komsa,
M.; Kuhn, J.; Lin, H.; Oncley, S.; Penn, M.; Rimmele, T.; Soltau,
D.; Streander, K.
2004AAS...204.6909H Altcode: 2004BAAS...36..795H
We present the latest results and current status of the site survey
portion of the Advanced Technology Solar Telescope (ATST) project. The
ATST will provide high resolution solar data in the visible and IR. The
site is a major factor determining the performance of the telescope. The
most critical site characteristics are the statistics of daytime seeing
quality and sky clarity. These conditions are being measured by a suite
of instruments at three sites (Big Bear, Haleakala, La Palma). These
sites were chosen from a set of six that have been tested starting in
November 2001. The instrumentation includes a solar differential image
motion monitor, an array of scintillometers, a miniature coronagraph,
a dust monitor, and a weather station. The analysis of the data provides
an estimate of the seeing as a function of height near the ground. We
will present the latest results of the analysis of the survey data set.
---------------------------------------------------------
Title: IR Vector Magnetic Fields I: Instrumental Polarization
Correction
Authors: Jaeggli, S. A.; Penn, M. J.
2004AAS...204.3706J Altcode: 2004BAAS...36R.709J
Instrumental polarization is evident in the spectra of active
region 10008 taken with the CSUN-NSO IR camera at the McMath-Pierce
telescope on June 24, 2002. Several iron lines near 15650 Å in the
spectra exhibit Zeeman splitting. Using a technique described by Kuhn
et. al. (1994) the original polarization is restored. For all Zeeman
split lines in the spectra the corrected Stokes profiles for the Q and
U components show symmetry, while Stokes V is made antisymmetric with
no central component. <P />The observed Stokes vector is related to the
true Stokes vector through the formula S<SUB>true</SUB> = M<SUP>-1</SUP>
S<SUB>obs</SUB> where M<SUP>-1</SUP> is the inverse Mueller matrix. The
correction coefficients from the Kuhn method are used to compute the
inverse Mueller matrix for light path of the entire system. The expected
inverse Mueller matrix is computed for the telescope at each scan time
using a simple model described by Bernasconi (1997) but assuming the
n and k values of the index of refraction are the same for each mirror
surface. A least squares technique is used to fit this telescope model
to the measured inverse Mueller matrix for the system. The telescope
model can account for most of the measured cross-talk except for the
observed Stokes Q to Stokes V cross-talk which is thought to occur in
the polarimeter.
---------------------------------------------------------
Title: IR Vector Magnetic Fields II: Atomic and Molecular Line
Polarization in a Sunspot
Authors: Penn, M. J.; Jaeggli, S. A.; Henney, C. J.; Walton, S. R.;
Ceja, J. A.
2004AAS...204.3705P Altcode: 2004BAAS...36..709P
Full Stokes I,Q,U and V measurements of the active region NOAA 10008
were taken from 21-27 June 2002 at the NSO Kitt Peak McMath/Pierce
solar telescope using the CSUN/NSO HgCdTe IR camera and polarimeter at
1565nm. The data is corrected for instrumental polarization as discussed
in Paper I. Here the initial analysis of the atomic and molecular
line polarization data is presented. <P />Inversion of the Fe I g=3
1564.8nm line data with a modified Skumanich and Lites Milne-Eddington
technique is used to measure photospheric magnetic field parameters. A
sequence of scans covering several hours of time shows evolution of
the magnetic field. Examination of the linear polarization of the OH
1565.2nm shows curious temporal variation which results in a magnetic
azimuth radically different from that measured using the photospheric
lines. (Similar OH polarization behavior is seen in data from the
CSUN San Fernando Observatory vacuum telescope taken with the CSUN/NSO
camera in active region NOAA 10069 on 12 Aug 2002.) Finally, maps of
the CN 1564.6nm Stokes I line shift show rapid penumbral Evershed
flows and a curious signal in the sunspot umbra. <P />Some of this
work is carried out through the National Solar Observatory Research
Experiences for Undergraduate (REU) site program, which is co-funded
by the Department of Defense in partnership with the National Science
Foundation REU Program.
---------------------------------------------------------
Title: Magnetic Source of 16 Mar 2009 Filament Eruption: An Imagined
VSO Study
Authors: Penn, M. J.
2004AAS...204.5202P Altcode: 2004BAAS...36..754P
There have been many studies of the famously geo-effective CME of 16
Mar 2009 and the associated filament eruption. The general features of
the current model, where global sub-surface flows transport magnetic
fields which weaken the overlying magnetic arcade and allow a tiny
intra-network dipole to trigger the eruption, are mentioned. Particular
emphasis is placed on the performance of the Virtual Solar Observatory
with respect to this event. The multi-wavelength and multiple spatial
scale nature of the VSO-retrieved data is shown to be essential to
several studies of the filament, flare and CME. A movie-based VSO user
interface facilitated data retrieval. Raw data access was critical in
several cases, and pointers to the relevant calibration data were very
helpful. The ability to retrieve magnetic extrapolation models from the
VSO system aided in several studies of the filament eruption trajectory,
as did the available in-situ data. Finally, the meshing of the public
data with the open-PI data from several observatories was helpful,
though improvements are suggested.
---------------------------------------------------------
Title: Extinction and Sky Brightness at Two Solar Observatories
Authors: Penn, M. J.; Lin, H.; Schmidt, A. M.; Gerke, J.; Hill, F.
2004SoPh..220..107P Altcode:
The Advanced Technology Solar Telescope site survey Sky Brightness
Monitor simultaneously images the solar disk and the sky to about
8 solar radii in four wavelengths at 450, 530, 890 and 940 nm. One
day of data from Mees Solar Observatory on Haleakala and from the
National Solar Observatory at Sacramento Peak (Sunspot, New Mexico)
are analyzed. Both sites show strong Rayleigh extinction, but while
Haleakala shows a larger aerosol component, Sunspot shows a large
variation in the aerosol component. Overall the Haleakala extinction
varies as λ<SUP>−2</SUP> whereas the Sunspot extinction changes
from about λ<SUP>−3.5</SUP> to about λ<SUP>−2</SUP>, suggesting
an increasing aerosol component during the day. Water vapor absorption
measurements from both sites are similar, though Sunspot shows larger
time variations than Haleakala. The instrument-corrected sky brightness
from both sites show comparable values, and again the Sunspot data show
more variations. The sky brightness values show a radial dependence
of sky brightness of r<SUP>−0.1</SUP> at Haleakala, but a dependence
of r<SUP>−1.0</SUP> at Sunspot. The wavelength variation of the sky
brightness at Haleakala is relatively constant at λ<SUP>−1.5</SUP>
but varies at Sunspot from λ<SUP>−1.5</SUP> to λ<SUP>−0.1</SUP>
again suggesting an increasing aerosol contribution during the day
at Sunspot. Finally, dust measurements near the ground are compared
with the extinction wavelength exponent for data taken at Haleakala
on 24 Feb. 2003. The measurements suggest more large dust particles
are present near the ground than averaged over the whole air column.
---------------------------------------------------------
Title: Synergy of Research and EPO Programs at NSO
Authors: Balasubramaniam, K. S.; Keil, S. L.; Penn, M. J.; Dooling,
D.; Piano, P.; Diehl, J.; Hunter, R.
2003AGUFMED51C1215B Altcode:
The National Solar Observatory with its facilities at Sunspot, NM and
Tucson, AZ runs an extensive education and public outreach effort. Much
of these efforts are coupled research and education efforts aimed
across a spectrum that spans through school teachers, school students,
undergraduate and graduate researchers, and the public. In this paper,
we will describe the benefits and challenges the NSO program faces,
and future prospects of these programs.
---------------------------------------------------------
Title: Imaging Spectropolarimetry of Ti I 2231 nm in a Sunspot
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
Livingston, W.
2003SoPh..215...87P Altcode:
Spectro-polarimetric observations at 2231 nm were made of NOAA 10008
near the west solar limb on 29 June 2002 using the National Solar
Observatory McMath-Pierce Telescope at Kitt Peak and the California
State University Northridge - National Solar Observatory infrared
camera. Scans of spectra in both Stokes I and Stokes V were collected;
the intensity spectra were processed to remove strong telluric
absorption lines, and the Stokes V umbral spectra were corrected for
instrumental polarization. The sunspot temperature is computed using
the continuum contrast and umbral temperatures down to about 3700 K are
observed. A strong Ti i line at 2231.0 nm is used to probe the magnetic
and velocity fields in the spot umbra and penumbra. Measurements of the
Ti i equivalent width versus plasma temperature in the sunspot agree
with model predictions. Zeeman splitting measurements of the Stokes I
and Stokes V profiles show magnetic fields up to 3300 G in the umbra,
and a dependence of the magnetic field on the plasma temperature
similar to that which was seen using Fe i 1565 nm observations of the
same spot two days earlier. The umbral Doppler velocity measurements
are averaged in 16 azimuthal bins, and no radial flows are revealed to
a limit of ± 200 m s<SUP>−1</SUP>. A Stokes V magnetogram shows a
reversal of the line-of-sight magnetic component between the limb and
disk center sides of the penumbra. Because the Ti i line is weak in
the penumbra, individual spectra are averaged in azimuthal bins over
the entire penumbral radial extent. The averaged Stokes V spectra show
a magnetic reversal as a function of sunspot azimuthal angle. The mean
penumbral magnetic field as measured with the Stokes V Zeeman component
splitting is 1400 G. Several weak spectral lines are observed in the
sunspot and the variation of the equivalent width versus temperature
for four lines is examined. If these lines are from molecules, it is
possible that lines at 2230.67, 2230.77, and 2231.70 nm originate from
OH, while the line at 2232.21 nm may originate from CN.
---------------------------------------------------------
Title: Weak Infrared Molecular Lines Reveal Rapid Outflow in Cool
Magnetic Sunspot Penumbral Fibrils
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
Livingston, W.
2003ApJ...590L.119P Altcode:
New imaging spectropolarimetric observations of the Evershed flow
in sunspot penumbrae using weak infrared molecular absorption lines
are presented. A plane-polar coordinate system in the sunspot frame
is defined, allowing averaging of many raw spectra. Molecular lines
show Doppler shifts implying typical horizontal outflow speeds of 6
and up to 9 km s<SUP>-1</SUP>. The Ti I polarimetric spectra show the
same rapid outflow and suggest an average penumbral magnetic field
strength of 1400 G. While these observations show Doppler shifts of
the entire line profile, the velocities are in better agreement with
previous measurements from spectral line asymmetries.
---------------------------------------------------------
Title: Weak IR Lines Reveal Rapid Outflow in Cool Magnetic Penumbra
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
Livingston, W.
2003SPD....34.1106P Altcode: 2003BAAS...35..827P
New imaging spectropolarimetric observations of the Evershed flow in
sunspot penumbrae using weak infrared molecular absorption lines are
presented. A plane-polar coordinate system in the sunspot frame is
defined, allowing averaging of many raw spectra. Molecular lines show
Doppler shifts implying typical horizontal outflow speeds of 6 to 9
km/sec. The Ti I polarimetric spectra show the same rapid outflow
and suggest an average penumbral magnetic field strength of 1400
Gauss. While these observations show Doppler shifts of the entire
line profile the velocities are in better agreement with previous
measurements from spectral line asymmetries.
---------------------------------------------------------
Title: Temperature Dependence of Molecular Line Strengths and Fe i
1565 nm Zeeman Splitting in a Sunspot
Authors: Penn, M. J.; Walton, S.; Chapman, G.; Ceja, J.; Plick, W.
2003SoPh..213...55P Altcode:
Spectroscopic observations at 1565 nm were made in the eastern half of
the main umbra of NOAA 9885 on 1 April 2002 using the National Solar
Observatory McMath-Pierce Telescope at Kitt Peak with a tip-tilt
image stabilization system and the California State University
Northridge-National Solar Observatory infrared camera. The line depth
of the OH blend at 1565.1 nm varies with the observed continuum
temperature; the variation fits previous observations except that
the continuum temperature is lower by 600 K. The equivalent width of
the OH absorption line at 1565.2 nm shows a temperature dependence
similar to previously published umbral molecular observations at 640
nm. A simple model of expected OH abundance based upon an ionization
analogy to molecular dissociation is produced and agrees well with the
temperature variation of the line equivalent width. A CN absorption
line at 1564.6 nm shows a very different temperature dependence, likely
due to complicated formation and destruction processes. Nonetheless a
numerical fit of the temperature variation of the CN equivalent width
is presented. Finally a comparison of the Zeeman splitting of the Fe i
1564.8 nm line with the sunspot temperature derived from the continuum
intensity shows an umbra somewhat cooler for a given magnetic field
strength than previous comparisons using this infrared 1564.8 nm line,
but consistent with these previous infrared measurements the umbra is
hotter for a given magnetic field strength than magnetic and temperature
measurements at 630.2 nm would suggest. Differences between the 630.2
nm and 1564.8 nm umbral temperature and magnetic field relations are
explained with the different heights of formation of the lines and
continua at these wavelengths.
---------------------------------------------------------
Title: Science Objectives and Technical Challenges of the Advanced
Technology Solar Telescope (Invited review)
Authors: Rimmele, T.; Keil, S. L.; Keller, C.; Hill, F.; Penn, M.;
Goodrich, B.; Hegwer, S.; Hubbard, R.; Oschmann, J.; Warner, M.;
Dalrymple, N.; Radick, R.; Atst Team
2003ASPC..286....3R Altcode: 2003ctmf.conf....3R
No abstract at ADS
---------------------------------------------------------
Title: Stokes V Profiles in a Post-flare Ca II 854.2nm Downflow
Authors: Penn, M. J.; Jones, H. P.
2003ASPC..286..355P Altcode: 2003ctmf.conf..355P
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopic Detection of the 3.934 Micron Line of Si IX in
the Solar Corona
Authors: Judge, P. G.; Tomczyk, S.; Livingston, W. C.; Keller, C. U.;
Penn, M. J.
2002ApJ...576L.157J Altcode:
We report the detection of the
2s<SUP>2</SUP>2p<SUP>2</SUP><SUP>3</SUP>P<SUB>1-->0</SUB> line of
Si IX using the McMath-Pierce telescope on Kitt Peak. Observations
were made of the solar disk and at various heights above the limb
between 2002 May 13 and 17, under nonideal sky conditions, using the
13.5 m vertical spectrograph and an InSb single-diode detector. We
report a new rest wavelength for the line and discuss its potential
use as a diagnostic of coronal magnetic fields using ground-based
telescopes. Our observations give λ<SUB>rest</SUB>=3.93434+/-0.00007
μm, consistent with earlier less accurate values, but it places the
blue wing of the line under a strong telluric N<SUB>2</SUB>O line. In
the active regions observed, the line's intensity is comparable to or
larger than predicted in earlier work for the quiet Sun.
---------------------------------------------------------
Title: Polarization of the Sodium D-Lines in Mercury's Atmosphere
Authors: Allen, J. E., Jr.; Penn, M. J.; Michael, B. P.; Branston,
D.; Ceja, J.
2002DPS....34.0803A Altcode: 2002BAAS...34..847A
Observations of the linear polarization of the sodium D-lines in the
atmosphere of Mercury were made using a polarization analysis package
with the Fabry-Perot interferometer at the Dunn Solar Telescope. The
spectropolarimetric data resulting from these high-resolution images
were subsequently confirmed using a comparable polarization package
with the Solar Stellar Spectrograph at the McMath-Pierce Telescope. The
observations are analogous to similar measurements of these lines
in the Sun's atmosphere, where they constitute part of the `second
solar spectrum'. Analysis of the data showed that the D1 line at 589
nm was depolarized, whereas the D2 line at 589.6 nm was polarized
at the continuum level, consistent with Hanle-effect depolarization
of the ground state and/or J-level quantum interference in the upper
state. The discovery of similar behavior in the Hermean sodium D-lines
suggests that the second solar spectrum is not unique to the Sun's
atmosphere, but may be more pervasive. This work supported by NASA
and the National Solar Observatory; the latter is operated by the
Association of Universities for Research in Astronomy, Inc. under
cooperative agreement with the National Science Foundation.
---------------------------------------------------------
Title: He I 1083nm Spectra of an Erupting Prominence
Authors: Penn, M. J.
2002AAS...200.3713P Altcode: 2002BAAS...34..696P
Observations were taken at the NSO/KP McMath/Pierce Telescope using
a new 256x256 HgCdTe array camera as part of a collaboration between
NSO and Cal State University Northridge. Spectra of the He I 1083nm
line were taken between 17:36-18:06 UT on 22 Mar 2002 of the active
region NOAA 9877 near the west limb. Doppler shifted flows of +/- 50
km/sec are seen near the active region sunspots. Line emission from an
erupting prominence is also seen in these data above the west limb;
rapid transverse motion as well as Doppler shifts of +/- 100 km/sec
and greater are observed. Sample data and a more detailed analysis
will be presented.
---------------------------------------------------------
Title: Infrared Spectroscopy from San Fernando Observatory: He I
1083 nm, O I 1316 nm, and Fe I 1565 nm
Authors: Penn, M. J.; Ceja, J. A.; Bell, E.; Frye, G.; Linck, R.
2002SoPh..205...53P Altcode:
Imaging spectroscopy of the Sun was carried out at the California
State University Northridge San Fernando Observatory using an InGaAs
near-IR video camera. Using the Si i 1082.71 nm and He i 1083.03 nm
lines the Evershed effect is measured simultaneously in the photosphere
and the chromosphere for three sunspots; the speed of the Evershed
flow is measured to be between 3 to 8 times greater in the He i line
than in the Si i line, and the direction is radially inward in the
chromosphere and outward in the photosphere. Telluric absorption lines
prevented a meaningful measurement of O i 1128.7 nm limb emission, but
an upper limit of 20×10<SUP>−3</SUP> B<SUB>⊙</SUB> is measured for
chromospheric limb emission at O i 1316.3 nm. Zeeman splitting in Fe i
1564.9 nm was observed in six sunspot umbrae, and a linear relationship
between magnetic field and umbral continuum intensity is confirmed.
---------------------------------------------------------
Title: Status of CDMS search for dark matter WIMPs
Authors: Cabrera, B.; Abusaidi, R.; Akerib, D. S.; Barnes, P. D.;
Bauer, D. A.; Bolozdynya, A.; Brink, P. L.; Bunker, R.; Caldwell,
D. O.; Castle, J. P.; Chang, C.; Clarke, R. M.; Colling, P.; Cristler,
M. B.; Cummings, A.; da Silva, A.; Davies, A. K.; Dixon, R.; Dougherty,
B. L.; Driscoll, D.; Eichblatt, S.; Emes, J.; Gaitskell, R. J.;
Golwala, S. R.; Hale, D.; Haller, E. E.; Holmgren, D.; Hellmig, J.;
Huber, M. E.; Irwin, K. D.; Jochum, J.; Lipschultz, F. P.; Lu, A.;
Maloney, C.; Mandic, V.; Martinis, J. M.; Meunier, P.; Nam, S. W.;
Nelson, H.; Neuhauser, B.; Penn, M. J.; Perera, T. A.; Perillo Isaac,
M. C.; Pritychenko, B.; Ross, R. R.; Saab, T.; Sadoulet, B.; Sander,
J.; Seitz, D. N.; Shestople, P.; Shutt, T.; Smith, A.; Smith, G. W.;
Schnee, R. W.; Sonnenschein, A. H.; Spadafora, A. L.; Stockwell, W.;
Taylor, J. D.; White, S.; Yellin, S.; Young, B. A.
2001AIPC..586..107C Altcode: 2001tsra.conf..107C
We report on the latest results from the CDMS (cryogenic dark matter
search) experiment. The experiment uses superconducting particle
detectors, operated below 100 mK, to search for dark matter in the form
of weakly interacting massive elementary particles or WIMPs. These
detectors are either Si or Ge crystals, where the electron-hole
production and the phonon production are measured for each event,
allowing the discrimination of electron recoils (most backgrounds
due to gammas and betas) from nuclear recoils (due to WIMPs and
neutrons). We have recently reported new limits from the Stanford
shallow site experiment (CDMS-I) which explore supersymmetric models
where the lightest supersymmetric particle is often an excellent WIMP
candidate. We will also report on the Soudan deep site facility for
the CDMS-II experiment which is under construction, and on the status
of the CDMS-II detector fabrication. .
---------------------------------------------------------
Title: Limits on the Wimp-Nucleon Cross-Section from the Cryogenic
Dark Matter Search
Authors: Schnee, R. W.; Abusaidi, R.; Akerib, D. S.; Barnes, P. D.;
Bauer, D. A.; Bolozdynya, A.; Brink, P. L.; Bunker, R.; Cabrera, B.;
Caldwell, D. O.; Castle, J. P.; Chang, C.; Clarke, R. M.; Colling, P.;
Crisler, M. B.; Cummings, A.; da Silva, A.; Davies, A. K.; Dixon, R.;
Dougherty, B. L.; Driscoll, D.; Eichblatt, S.; Emes, J.; Gaitskell,
R. J.; Golwala, S. R.; Hale, D.; Haller, E. E.; Holmgren, D.; Hellmig,
J.; Huber, M. E.; Irwin, K. D.; Jochum, J.; Lipschultz, F. P.; Lu,
A.; Maloney, C.; Mandic, V.; Martinis, J. M.; Meunier, P.; Nam,
S. W.; Nelson, H.; Neuhauser, B.; Penn, M. J.; Perera, T. A.; Isaac,
M. C. Perillo; Pritychenko, B.; Ross, R. R.; Saab, T.; Sadoulet, B.;
Sander, J.; Seitz, D. N.; Shestople, P.; Shutt, T.; Smith, A.; Smith,
G. W.; Sonnenschein, A. H.; Spadafora, A. L.; Stockwell, W.; Taylor,
J. D.; White, S.; Yellin, S.; Young, B. A.
2001cosm.conf...99S Altcode:
The Cryogenic Dark Matter Search (CDMS) employs Ge and Si detectors to
search for WIMPs via their elastic-scattering interactions with nuclei
while discriminating against interactions of background particles. CDMS
data, accounting for the neutron background, give limits on the
spin-independent WIMP-nucleon elastic-scattering cross-section that
exclude unexplored parameter space above 10 GeV c<SUP>-2</SUP> WIMP
mass and, at > 75% CL, the entire 3σ allowed region for the WIMP
signal reported by the DAMA experiment. The move to a deep site in
2001 should improve the experiment's sensitivity by ~ 100X.
---------------------------------------------------------
Title: Helioseismic Holography and a Study of the Process of Magnetic
Flux Disappearance in Canceling Bipoles
Authors: Lindsey, Charles; Harvey, Karen L.; Braun, D.; Jones, H. P.;
Penn, M.; Hassler, D.
2001STIN...0156300L Altcode:
Project 1: We have developed and applied a technique of helioseismic
holography along the lines of originally set out in our proposal. The
result of the application of this diagnostic technique to solar activity
and the quiet Sun has produced a number of important discoveries:
(1) acoustic moats surrounding sunspots; (2) acoustic glories
surround large active regions; (3) acoustic condensations beneath
active regions; and (4) temporally-resolve acoustic images of a solar
flare. These results have been published in a series of papers in the
Astrophysical Journal. We think that helioseismic holography is now
established as the most powerful and discriminating diagnostic in local
helioseismology. Project 2: We conducted a collaborative observational
program to define the physical character and magnetic geometry of
canceling magnetic bipoles aimed at determining if the cancellation
process is the result of submergence of magnetic fields. This assessment
is based on ground-based observations combining photospheric and
chromospheric magnetograms from NSO/KP, BBSO, and SOHO-MDI, and EUV
and X-ray images from SOHO EIT/CDS, Yohkoh/SXT, and TRACE. Our study
involves the analysis of data taken during three observing campaigns to
define the height structure of canceling bipoles inferred from magnetic
field and intensity images, and how this varies with time. We find
that some canceling bipoles can be explained by the submerge of their
magnetic flux. A paper on the results of this analysis will be presented
at an upcoming scientific meeting and be written up for publication.
---------------------------------------------------------
Title: An Erupting Active Region Filament: Three-Dimensional
Trajectory and Hydrogen Column Density
Authors: Penn, M. J.
2000SoPh..197..313P Altcode:
From 15:33 through 16:02 UT on 13 June 1998, observations of an erupting
filament as it crossed solar disk center were obtained with the NSO/KPVT
and SOHO/CDS instruments as part of the SOHO Joint Observing Program
70. Context observations show that this event was the eruption of
the north-east section of a small active region filament associated
with NOAA 8237, that the photospheric magnetic field was changing
in this active region between 12-14 June 1998, and that a coronal
Moreton-wave disk event occurred, as well as a white-light CME off the
south-west solar limb. The NSO/KPVT imaging spectroscopy data covered
512 × 512 arc sec of the disk center and were spectrally centered
at the He i 1083 nm line and captured ± 1.0 nm of surrounding solar
spectrum. The He i absorption line is seen blue-shifted to velocities
of between 200 and 300 km s<SUP>−1</SUP>. The true solar trajectory
of the eruption is obtained by using the projected solar coordinates
and by integrating the Doppler velocity. The filament travels with a
total velocity of about 300 km s<SUP>−1</SUP> along a path inclined
roughly 49 deg to the solar surface and rises to a height of just over
1.5 solar radii before it becomes too diffuse to follow. The filament
also shows internal motions with multiple Doppler components shifted
by ± 25 km s<SUP>−1</SUP>. Finally, the KPVT data show no Stokes V
profiles in the Doppler-shifted He i 1083.03 nm absorption to a limit
of roughly 3×10<SUP>−3</SUP> times the continuum intensity. The
SOHO/CDS scanned the center of the KPVT FOV using seven EUV lines;
Doppler-shifted filament emission is seen in lines from He i 58.4
nm, He ii 30.4 nm, O iv 55.5 nm, O v 63.0 nm, Ne vi 56.3 nm, and Mg
x 61.0 nm representing temperatures from about 2×10<SUP>4</SUP>K
through 1×10<SUP>6</SUP>K. Bound-free continuum absorption from H
i, without confusion from foreground emission and line emission, is
seen as the filament obscures underlying chromospheric emission. A
fit to the wavelength dependence of the absorption from five lines
between 55.5 to 63.0 nm yields a column density ξ<SUB>H </SUB>
I =4.8±2.5×10<SUP>17</SUP> cm<SUP>−2</SUP>. Spatial maps show
that this filament absorption is more confined than the regions which
show emission.
---------------------------------------------------------
Title: A New Precise Measurement of the Coronal Magnetic Field
Strength
Authors: Lin, Haosheng; Penn, Matthew J.; Tomczyk, Steven
2000ApJ...541L..83L Altcode:
Magnetism dominates the structure and dynamics of the solar
corona. Current theories suggest that it may also be responsible for
coronal heating. Despite the importance of the magnetic field in the
physics of the corona and despite the tremendous progress made recently
in the remote sensing of solar magnetic fields, reliable measurements of
the coronal magnetic field strength and orientation do not exist. This
is largely due to the weakness of coronal magnetic fields, previously
estimated to be on the order of 10 G, and the difficulty associated
with observing the extremely faint solar corona emission. Using a
very sensitive infrared spectropolarimeter to observe the strong
near-infrared coronal emission line Fe XIII λ10747 above active
regions, we have succeeded in measuring the weak Stokes V circular
polarization profiles resulting from the longitudinal Zeeman effect
of the magnetic field of the solar corona. From these measurements,
we infer field strengths of 10 and 33 G from two active regions at
heights of h=0.12 R<SUB>solar</SUB> and h=0.15 R<SUB>solar</SUB>,
respectively. We expect that this measurement technique will allow,
in the near future, the routine precise measurement of the coronal
magnetic field strength with application to many critical problems in
solar coronal physics.
---------------------------------------------------------
Title: High-Resolution Spectra of Sodium in Mercury's Atmosphere
Authors: Allen, J. E., Jr.; Penn, M. J.; Michael, B. P.; Branston, D.
2000DPS....32.2406A Altcode: 2000BAAS...32.1036A
High-resolution (R ~100,000) spectral images of the sodium (Na) D1 and
D2 lines in Mercury's atmosphere were obtained using a Fabry-Perot
interferometer on the Dunn Solar Telescope at Sacramento Peak,
NM. Observations were made from May 29 to June 4, 2000 when Mercury
was at ~20.5 and 23.2 degrees E elongation with a radial velocity of
~-34.9 and -33.2 km/s, respectively. Preliminary analysis of the data
suggests the atmosphere was optically thicker than when these emissions
were first observed (Potter and Morgan 1985). This is attributed to the
fact that those observations were made close to solar minimum, whereas
our measurements were made closer to solar maximum. The observed D1 and
D2 emission lines were blue shifted by ~0.74 and 0.71 Å, respectively,
corresponding to Doppler shifts of ~-37.65 and -36.29 km/s. <P />Potter,
A. E. and Morgan, T. H. 1985, Science 229, 651.
---------------------------------------------------------
Title: Exclusion Limits on the WIMP-Nucleon Cross Section from the
Cryogenic Dark Matter Search
Authors: Abusaidi, R.; Akerib, D. S.; Barnes, P. D.; Bauer, D. A.;
Bolozdynya, A.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell,
D. O.; Castle, J. P.; Clarke, R. M.; Colling, P.; Crisler, M. B.;
Cummings, A.; da Silva, A.; Davies, A. K.; Dixon, R.; Dougherty, B. L.;
Driscoll, D.; Eichblatt, S.; Emes, J.; Gaitskell, R. J.; Golwala,
S. R.; Hale, D.; Haller, E. E.; Hellmig, J.; Huber, M. E.; Irwin,
K. D.; Jochum, J.; Lipschultz, F. P.; Lu, A.; Mandic, V.; Martinis,
J. M.; Nam, S. W.; Nelson, H.; Neuhauser, B.; Penn, M. J.; Perera,
T. A.; Perillo Isaac, M. C.; Pritychenko, B.; Ross, R. R.; Saab,
T.; Sadoulet, B.; Schnee, R. W.; Seitz, D. N.; Shestople, P.; Shutt,
T.; Smith, A.; Smith, G. W.; Sonnenschein, A. H.; Spadafora, A. L.;
Stockwell, W.; Taylor, J. D.; White, S.; Yellin, S.; Young, B. A.
2000PhRvL..84.5699A Altcode: 2000astro.ph..2471C
The Cryogenic Dark Matter Search (CDMS) employs Ge and Si detectors
to search for weakly interacting massive particles (WIMPs) via their
elastic-scattering interactions with nuclei while discriminating against
interactions of background particles. CDMS data, accounting for the
neutron background, give limits on the spin-independent WIMP-nucleon
elastic-scattering cross section that exclude unexplored parameter space
above 10 GeV/c<SUP>2</SUP> WIMP mass and, at >75% C.L., the entire
3σ allowed region for the WIMP signal reported by the DAMA experiment.
---------------------------------------------------------
Title: An Erupting Active Region Filament: Three-Dimensional
Trajectory and Hydrogen Column Density
Authors: Penn, M. J.
2000SPD....31.0268P Altcode: 2000BAAS...32..823P
From 15:33-16:02 UT on 13 June 1998 observations of an erupting filament
as it crossed solar disk center were obtained with the NSO/KPVT and
SoHO/CDS instruments as part of the SoHO Joint Observing Program
70. Context observations show that this event was the eruption of the
north-east section of a small active region filament associated with
NOAA 8237, that the photospheric magnetic field was changing in this
active region from 12 through 14 June 1998, that a coronal Moreton-wave
disk event occurred, as well as a white-light CME off the south-west
solar limb. The NSO/KPVT imaging spectroscopy sho the He I 1083 nm
absorption line blue-shifted to velocities of between 200 and 300 km
s<SUP>-1</SUP>. The true solar trajectory of the eruption is obtained
by using the projected solar coordinates and by integrating the Doppler
velocity. The filament travels with a total velocity of about 300 km
s<SUP>-1</SUP> along a path inclined roughly 49 degrees to the solar
surface and rises to a height of just over 1.5 solar radii. The KPVT
data show no Stokes V profiles in the Doppler shifted He I 1083 nm
absorption to a limit of roughly 3 x 10<SUP>-3</SUP> times the continuum
intensity. The SoHO/CDS data scanned the center of the KPVT FOV using
seven EUV lines; Doppler shifted filament emission is seen in six
lines from representing temperatures from about 2 x 10<SUP>4</SUP>K
through 1 x 10<SUP>6</SUP>K. Bound-free continuum absorption from H
I, free from confusion from foreground emission and line emission,
is seen as the filament obscures underlying chromospheric emission. A
fit to the wavelength dependence of the absorption from five lines
between 55.5 to 63.0 nm yields a column density ξ <SUB>HI</SUB> = 1.7
x 10<SUP>18</SUP>cm<SUP>-2</SUP>. Spatial maps show that this filament
absorption is more confined than the regions which show emission. This
work was made possible by 1997 and 1999 SoHO Guest Investigator awards
NASA #W-19,142 Basic and NASA NAG5-8004.
---------------------------------------------------------
Title: Does Magnetic Flux Submerge at Flux Cancelation Sites?
Authors: Harvey, Karen L.; Jones, Harrison P.; Schrijver, Carolus J.;
Penn, Matthew J.
1999SoPh..190...35H Altcode:
Simultaneous measurements of the magnetic fields in the photosphere and
chromosphere were used to investigate if magnetic flux is submerging
at sites between adjacent opposite polarity magnetic network elements
in which the flux is observed to decrease or `cancel'. These data
were compared with chromospheric and coronal intensity images to
establish the timing of the emission structures associated with these
magnetic structures as a function of height. We found that most of
the cancelation sites show either that the bipole is observed longer
in the photosphere than in the chromosphere and corona (44%) or that
the timing difference of the disappearance of the bipole between these
levels of the atmosphere is unresolved. The magnetic axis lengths of the
structures associated with the cancelation sites are on average slightly
smaller in the chromosphere than the photosphere. These observations
suggest that magnetic flux is retracting below the surface for most,
if not all, of the cancelation sites studied.
---------------------------------------------------------
Title: Comparison of Fe λ5303, λ6374 and λ7892 spectral line
observations in a coronal hole and streamer
Authors: Wood, Christine H.; Habbal, Shadia R.; Esser, Ruth; Penn,
Matthew
1999AIPC..471..293W Altcode: 1999sowi.conf..293W
We present intensity and line width measurements of the Fe X λ6374,
Fe XI λ7892 and Fe XIV λ5303 lines between 1.03 and 1.4 R<SUB>s</SUB>
in a coronal hole and a streamer. The observations were made at the
National Solar Observatory at Sacramento Peak on 26 February 1998. In
the coronal hole, only the Fe X line was observed; an upper limit
of 10<SUP>6</SUP> K for the electron temperature and 28 km/s for the
amplitude of nonthermal motions was inferred from the Fe X measurements
at 1.06 R<SUB>s</SUB>. While all three lines were observed in the
streamer, the unique result was that the width of the Fe XI line
increased with heliocentric distance as opposed to a decrease in the
Fe X and Fe XIV line widths. We interpret this as evidence for the
existence of multitemperature static plasmas, and a solar wind outflow
at the streamer base.
---------------------------------------------------------
Title: New Measurements of the Solar Limb Emission in the O I 777.4
and 844.6 Nanometer Lines
Authors: Penn, M. J.
1999ApJ...518L.131P Altcode:
Slit spectra of the solar limb emission in the 777.4 and 844.6 nm O
I lines are calibrated against the solar disk center brightness. Data
from CCD spectrograph instruments at two different observatories show
limb emission with identical line intensities and measure a value of
R<SUB>4</SUB>≡ΣI(844.6 nm)/ΣI(777.4 nm)=0.20+/-0.02, very different
from the ratios computed from early photographic measurements of these
lines. Implied by this new value of R<SUB>4</SUB> is that O I lines in
the solar chromosphere are formed in regions with electron densities
log(N<SUB>e</SUB>)>11.5 and that collisional excitation is more
important than the photoexcitation by accidental resonance mechanism.
---------------------------------------------------------
Title: Disk Center Eruptive Filament Line Profile Observations
Authors: Penn, M. J.
1999AAS...19410106P Altcode: 1999BAAS...31..999P
From 15:33-15:54 UT on 13 June 1998 observations of an erupting
filament at disk center were obtained with the NSO/KPVT, SoHO/CDS, and
TRACE instruments as part of the SoHO Joint Observing Program 70. The
NSO/KPVT imaging spectroscopy data scanned 512x512 arcsec of the solar
surface at disk center and were spectrally centered at the He I 1083 nm
line and captured +/- 1.0 nm of surrounding solar spectrum. The He I
absorption line is seen blue-shifted to velocities of between 200 and
300 km/sec. The true solar trajectory of the eruption is obtained by
using the projected solar N/S and E/W coordinates and by integrating
the Doppler velocity. The filament travels along a path inclined
roughly 45 degrees to the solar surface to a height of about 1.5 solar
radii before it becomes too diffuse to follow. The filament also shows
internal motions (untwisting?) with multiple Doppler components shifted
by +/- 25 km/sec. The SoHO/CDS data scanned the region in seven EUV
lines; results from these data will also be presented. Finally, the
TRACE data shows the morphology of the eruption in the EUV lines of
Fe IX and Fe XII. Evolution of the hot coronal plasma is evident,
and evolving dark regions seem to show the cool plasma transverse
motions. The NSO/KPVT data presented are produced cooperatively by
NSF/NOAO, NASA/GSFC and NOAA/SEL. This work is is part of a 1997 and
a 1999 SoHO Guest Investigator award.
---------------------------------------------------------
Title: Preliminary limits on the WIMP-nucleon cross section from
the cryogenic dark matter search (CDMS).
Authors: Akerib, D. S.; Barnes, P. D., Jr.; Bauer, D. A.; Brink, P. L.;
Cabrera, B.; Caldwell, D. O.; Clarke, R. M.; da Silva, A.; Davies,
A. K.; Dougherty, B. L.; Irwin, K. D.; Gaitskell, R. J.; Golwala,
S. R.; Haller, E. E.; Jochum, J.; Knowlton, W. B.; Kuzminov, V.;
Nam, S. W.; Novikov, V.; Penn, M. J.; Perera, T. A.; Ross, R. R.;
Sadoulet, B.; Schnee, R. W.; Shutt, T.; Smith, A.; Sonnenschein,
A. H.; Spadafora, A. L.; Stockwell, W. K.; Yellin, S.; Young, B. A.
1999NuPhS..70...64A Altcode: 1997astro.ph.12343A
The authors are conducting an experiment to search for WIMPs, or
weakly-interacting massive particles, in the galactic halo using
terrestrial detectors. This generic class of hypothetical particles,
whose properties are similar to those predicted by extensions of
the standard model of particle physics, could comprise the cold
component of non-baryonic dark matter. The authors describe the
experiment, which is based on cooled germanium and silicon detectors
in a shielded low-background cryostat. The detectors achieve a high
degree of background rejection through the simultaneous measurement
of the energy in phonons and ionization. Using exposures on the order
of one kilogram-day from initial runs of the experiment, the authors
have achieved (preliminary) upper limits on the WIMP-nucleon cross
section that are comparable to much longer runs of other experiments.
---------------------------------------------------------
Title: Results of the Cryogenic Dark Matter Search (CDMS) Obtained
with Thermistor-Instrumented Germanium Calorimeters
Authors: Sonnenschein, A.; Bauer, D. A.; Caldwell, D. O.; Nelson, H.;
Yellin, S.; Brink, P. L.; Cabrera, B.; Clarke, R. M.; Colling, P.;
Davies, A. K.; Irwin, K. D.; Nam, S. W.; Penn, M. J.; Akerib, D. S.;
Bolodyaynya, A.; Perera, T. A.; Schnee, R. W.; Crisler, M. B.; Dixon,
R.; Eichblatt, S.; da Silva, A.; Gaitskell, R. J.; Golwala, S. R.;
Jochum, J.; Barnes, P. D., Jr.; Sadoulet, B.; Shutt, T.; Spadafora,
A. L.; Stockwell, W. K.; Haller, E. E.; Knowlton, W. B.; Ross, R. R.;
Smith, A.; Smith, G.; Young, B. A.; Neuhausser, B.; Lipschultz, F.
1999idm..conf..347S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Results and status of the Cryogenic Dark Matter Search (CDMS).
Authors: Schnee, R. W.; Akerib, D. S.; Barnes, P. D., Jr.; Bauer,
D. A.; Brink, P. L.; Cabrera, B.; Caldwell, D. O.; Clarke, R. M.;
Colling, P.; Crisler, M. B.; Dasilva, A.; Davies, A. K.; Dougherty,
B. L.; Eichblatt, S.; Irwin, K. D.; Gaitskell, R. J.; Golwala, S. R.;
Haller, E. E.; Jochum, J.; Knowlton, W. B.; Kuzminov, V.; Nam, S. W.;
Novikov, V.; Penn, M. J.; Perera, T. A.; Ross, R. R.; Sadoulet, B.;
Shutt, T.; Smith, A.; Sonnenschein, A. H.; Spadafora, A. L.; Stockwell,
W. K.; Yellin, S.; Young, B. A.
1998PhR...307..283S Altcode:
The Cryogenic Dark Matter Search experiment uses cooled germanium
and silicon detectors for a direct search for weakly interacting
massive particles in our Galaxy. The novel detectors allow a high
degree of background rejection by discriminating between electron and
nuclear recoils through the simultaneous measurement of the energy
deposited in phonons and ionization. Exposures on the order of one
kilogram-day from initial runs of our experiment yield (preliminary)
upper limits on the WIMP-nucleon cross section that are comparable
to much longer runs of other experiments. Current and future runs
promise significant improvement, primarily due to improved detectors
and reduced surface-electron backgrounds.
---------------------------------------------------------
Title: Limits on the WIMP-Nucleon Cross Section from the Cryogenic
Dark Matter Search
Authors: Akerib, D. S.; Barnes, P. D., Jr.; Bauer, D. A.; Bolozdynya,
A.; Cabrera, B.; Caldwell, D. O.; Clarke, R. M.; Crisler, M.; da
Silva, A.; Davies, A. K.; Dixon, R.; Eichblatt, S.; Irwin, K. D.;
Gaitskell, R. J.; Golwala, S. R.; Haller, E. E.; Jochum, J.; Kuzminov,
V.; Kurylowicz, M.; Nam, S. W.; Penn, M. J.; Perera, T. A.; Ross,
R. R.; Saab, T.; Sadoulet, B.; Schnee, R. W.; Seitz, D.; Shutt, T.;
Smith, A.; Sonnenschein, A. H.; Spadafora, A. L.; White, S.; Yellin,
S.; Young, B. A.
1998tx19.confE.271A Altcode:
The Cryogenic Dark Matter Search (CDMS) aims to detect WIMPs in the
galactic halo by observation of elastic scattering interactions with
nuclei in germanium and silicon targets. CDMS uses novel cryogenic
detectors that actively reject typical radioactive backgrounds, and
thus is ultimately vastly more sensitive to WIMP interactions than
previous experiments. We present limits on the WIMP-nucleon elastic
scattering cross section based on data acquired during recent runs,
reflecting significant detector and background improvements.
---------------------------------------------------------
Title: Constraints on the Presence of WIMPs in the Galactic Halo
from the Cryogenic Dark Matter Search
Authors: Golwala, S. R.; Dasilva, A.; Gaitskell, R. J.; Hellmig, J.;
Jochum, J.; Seitz, D.; Smith, G.; Spadafora, A. L.; White, S.; Perillo
Isaac, M. C.; Ross, R. R.; Sadoulet, B.; Akerib, D. S.; Bolozdynya,
A.; Perera, T. A.; Schnee, R. W.; Barnes, P. D.; Bauer, D. A.; Bunker,
R.; Caldwell, D. O.; Nelson, H. N.; Sonnenschein, A. H.; Yellin,
S.; Brink, P. L.; Cabrera, B.; Clarke, R. M.; Colling, P.; Davies,
A. K.; Kurylowicz, M.; Nam, S. W.; Penn, M. J.; Saab, T.; Castle,
P.; Drury, L. O'C; Lipschultz, F. P.; Neuhauser, B. J.; Crisler, M.;
Dixon, R.; Eichblatt, S.; Haller, E. E.; Kuzminov, V.; Martinis, J.;
Irwin, K. D.; Shutt, T.; Smith, A.; Young, B. A.; CDMS Collaboration
1998AAS...193.6105G Altcode: 1998BAAS...30Q1337G
The Cryogenic Dark Matter Search (CDMS) aims to detect WIMPs in the
galactic halo by observation of elastic scattering interactions with
nuclei in germanium and silicon targets. CDMS uses novel cryogenic
detectors that actively reject typical radioactive backgrounds, and
thus is ultimately vastly more sensitive to WIMP interactions than
previous experiments. We present limits on the WIMP-nucleon elastic
scattering cross section based on data acquired during recent runs,
reflecting significant detector and background improvements.
---------------------------------------------------------
Title: The Helium Spectrum in the Quiet Sun: The January 16/17 and
May 7-13 1997 Coordinated SOHO/Ground-Based Observational Campaigns
Authors: Andretta, Vincenzo; Jordan, Stuart D.; Muglach, Karin;
Garcia, Adriana; Jones, Harrison P.; Penn, Matthew J.; Soltau, Dirk
1998ASPC..155..336A Altcode: 1998sasp.conf..336A
No abstract at ADS
---------------------------------------------------------
Title: Synoptic Coronal Temperature; Magnetic Field and He 11083
NM Observations
Authors: Penn, M.; Altrock, R. C.; Henry, T.; Guhathakurta, M.
1998ASPC..140..325P Altcode: 1998ssp..conf..325P
No abstract at ADS
---------------------------------------------------------
Title: Electron Temperature Distribution in Coronal Holes
Authors: Halas, C. D.; Habbal, S. R.; Penn, M.; Uitenbroek, H.; Esser,
R.; Altrock, R.; Guhathakurta, M.
1997AAS...191.7413H Altcode: 1997BAAS...29Q1326H
Knowledge of the electron temperature within coronal holes is extremely
important for constructing solar wind models and for understanding
the coronal heating process. We report on the two-dimensional CCD
observations of the Fe IX 4585, Fe X 6374, Fe XI 7892 and Fe XIV 5303
{ Angstroms} emission lines made using a coronagraph at the National
Solar Observatory at Sacramento Peak. These iron lines, which have
a peak formation temperature of 5 10(5) , 10(6) , 1.2 10(6) , and 2
10(6) K, respectively, allow the examination of different temperature
plasmas within the same large scale magnetic structure. To account for
possible line of sight ambiguities from hot material in the foreground
or background of the coronal hole, Yohkoh data were used to determine
the extent of the coronal hole along the line of sight. Intensities and
widths of these spectral lines as a function of heliocentric distance
out to 1.15 R_s will be presented. A comparison will be made between
coronal hole and streamer observations.
---------------------------------------------------------
Title: Comparison of NSO/KPVT 1083 NM and SOHO/CDS/SUMER Observations
of a Coronal Hole.
Authors: Jones, H. P.; Andretta, V.; Jordan, S. D.; Penn, M. J.
1997AAS...191.7304J Altcode: 1997BAAS...29.1321J
As part of SOHO Joint Observing Program 16 to study the solar formation
of Helium, coordinated observations of a coronal hole were obtained
on 17 Jan 97. In this paper, we compare the NSO/KPVT full-disk 1083 nm
spectroheliogram and a time sequence of spectra-spectroheliograms of the
coronal hole near the south solar pole with approximately cospatial and
cotemporal SOHO spatial-spectral data taken in He I (58.4 nm, CDS and
SUMER) and He II 30.4 nm (CDS) together with several transition-region
and coronal lines of CIII, OIII, OIV, MgIX, MgX, SiIX, and SiXII. We
have previously reported on correlations of line intensities. Here
we concentrate as well on Doppler shifts and, in particular, line
asymmetry in the He I 1083 nm line which shows augmented absorption
in the blue wing of the line within the coronal hole in the same sense
as reported by Dupree, Penn, and Jones (1996, ApJ 467, L121).
---------------------------------------------------------
Title: H i 1083 NM Oscillations and Downflows Near the North
Solar Pole
Authors: Penn, M. J.; Allen, C. L.
1997SoPh..174..359P Altcode:
Imaging spectroscopic data of the Sii 1082.7 nm (photospheric) and Hei
1083.0 nm (chromospheric) spectral lines were taken starting 22:05 UT
on 23 July, 1996 with the NASA/NSO Spectromagnetograph at the NSO/Kitt
Peak Vacuum Telescope. Observations were made near the north solar pole,
with a field of view of 100 by 400 arc sec and with a temporal cadence
of 53 s for 2 hr. Simple fitting to the line profiles measured the
line position, depth, and spectral full-width at half-maximum. Power
spectra of the velocity oscillations in each line were computed, and the
oscillation power in the 2 to 6 mHz frequency band versus view angle
was measured to search for horizontal oscillations. Horizontal waves
are not detected to limiting amplitudes (1σ) of 22 m s<SUP>-1</SUP>
in the chromosphere and 9 m s<SUP>-1</SUP> in the photosphere. These
values are used to estimate limits for the energy flux into the
corona. The amplitude of radial oscillations in the chromosphere is
twice that of the photosphere. No statistically meaningful oscillation
power is measured in the spectral parameters of the Hei line in the
emission shell seen above the continuum limb. Finally, rapidly evolving
red-shift events are observed in the Hei 1083 nm line on the disk;
these events are some sort of coronal rain, and there are about 40 of
these events on the solar disk at any moment.
---------------------------------------------------------
Title: Polarized Resonance Fluorescence of Comet Hale-Bopp
Authors: Allen, J. E., Jr.; Penn, M. J.; Branston, D.; Disanti, M. A.
1997DPS....29.3719A Altcode: 1997BAAS...29.1050A
Because it is basically a vector-related technique, polarization
spectroscopy can provide information not obtainable using traditional
spectroscopic methods. Typically polarization measurements are assoc-
iated with the characterization of the dust continuum. However, although
not as frequently studied, resonance fluorescence can also exhibit
polarization and the information can be related to physical properties
of the comet, e.g., magnetic-field direction. Observations of comet
Hale-Bopp were made shortly after perihelion (April 4 - 14, 1996) using
the Vacuum Tower Telescope at the National Solar Observatory in Sunspot,
NM. Images were taken through a variety of filters and spectra acquired
using the high-resolution horizontal spectrograph; in both cases data
were acquired with and without polarization analysis. Here we report
on the preliminary analysis of polarization images and spectra of the
sodium (Na) D<SUB>1</SUB> and D<SUB>2</SUB> lines and the Swan system
of C<SUB>2</SUB>.
---------------------------------------------------------
Title: The Height and Temporal Structure of X-Ray Bright Points
Authors: Harvey, K. L.; Penn, M.; Tarbell, T.; Saba, J.; Hassler,
D.; Moses, J. D.; Fludra, A.
1997SPD....28.0124H Altcode: 1997BAAS...29..883H
On April 12, 1996, several ground-based observatories, the Yohkoh/SXT
and the SOHO/MDI, EIT, SUMER, and CDS instruments participated in a
collaborative study of X-Ray Bright Points (XBPs). During a several
hour period, simultaneous images were obtained of an area centered
at N10E00. At NSO/KP, observations were made of the HeI 1083 nm line
profile from which we have derived the intensity at line center,
equivalent width, and the velocity at every 1 pixel (1.15 arc-seconds)
within an 8 x 8 arc-minute area. Our paper will present the results
of a comparison, spatially and temporally, of these data with changes
in the magnetic field observed by the MDI, intensities and velocities
observed with SUMER and CDS, and the intensity images observed by
the SXT and EIT. We will use this ensemble of intensity, magnetic
and velocity field images to derive the height structure of XBPS,
its variation as a function of time and relation to the associated
magnetic field configuration.
---------------------------------------------------------
Title: Quiet Sun He I 1083 NM Chromospheric Events
Authors: Penn, M. J.; Jones, H. P.
1997SPD....28.1303P Altcode: 1997BAAS...29..917P
Several types of flows are observed in the quiet solar chromosphere
using the He I 1083 nm absorption line with data from the
NSO/KPVT. Downflow events, termed “He Rain” are described by about
4 km/sec Doppler red-shift of the line, an increased line width,
and enhanced line absorption. The “He Rain” events begin with a
small, compact morphology then evolve during 500 seconds to become
extended and diffuse. The birth-rate of these “He Rain” events
suggests an association with either coronal loop interactions or
macrospicules. Loop-flow events observed with the He I 1083 nm line
show blue-shifts followed by a red-shift, an increased line width and
enhanced line absorption. The events follow curving trajectories with
sizes about 30 arcsec. These events occur much less frequently than
spicules, but may be associated with a type of spicule or some flow
along the local magnetic field. Recent observations of these quiet
Sun events and discussion of the associated coronal events will be
presented.
---------------------------------------------------------
Title: Reduction and Analysis of He I 1083 NM
Spectra-Spectroheliograms
Authors: Jones, H. P.; Winters, W. F.; Penn, M. J.; Schwitters, J. D.
1997SPD....28.0225J Altcode: 1997BAAS...29..897J
Over two decades of synoptic 1083 nm data from the National Solar
Observatory/Kitt Peak Vacuum Telescope (NSO/KPVT) attest to the fact
that satisfactory equivalent width images may be obtained from simple
sums over “line”and “continuum” bandpasses. However, much more care
is needed to extract Doppler velocity, line depth, and asymmetry since
the 1083 nm line typically has line depths of only a few percent and
is blended with both telluric water vapor and the red wing of a nearby
Si I line at 1082.8 nm. We present a new algorithm for analysis of He
I 1083 nm data obtained with the NASA/NSO Spectromagnetograph (SPM) at
the KPVT. A linear fit to intensity averages over bands near 1082.4 nm
and 1083.6 nm specifies the continuum intensity across the wavelength
domain of interest. The spectral algorithm currently used for 868.8 nm
SPM magnetograms computes line-center wavelengths and depths for the
strong adjacent telluric and Si lines. Quick fits of the damping wings
of these features together with a scaled profile of the weak water
vapor feature which is coincident in wavelength with the 1083 nm line
(Breckenridge and Hall, 1973: Solar Phys. 28, 15) are removed from the
spectral region containing the 1083 nm line. The spectral algorithm then
computes the central wavelength and line depth of the 1083 nm line. An
extension of this algorithm locates the bisector at the 0.35 central
line-depth position on the profile to compute a line asymmetry parameter
(Dupree, Penn, and Jones, 1976: ApJ 467, L121). We show sample results
of the algorithm applied both off-line to spectra-spectroheliograms
and on-line to spatial-spectral data as they are acquired.
---------------------------------------------------------
Title: Investigating the Formation of the Helium Spectrum with
Coordinated SOHO/Kitt Peak/Sacramento Peak Observations
Authors: Andretta, V.; Jordan, Stuart D.; Jones, Harrison P.; Penn,
Matthew J.
1997ESASP.404..163A Altcode: 1997cswn.conf..163A
No abstract at ADS
---------------------------------------------------------
Title: Looking for WIMPs: The Cryogenic Dark Matter Search
Authors: Jochum, J.; Barnes, P. D., Jr.; Dasilva, A.; Emes,
J.; Gaitskell, R. J.; Golwala, S. R.; Haller, E. E.; Ross, R. R.;
Sadoulet, B.; Seitz, D.; Shutt, T.; Smith, G.; Stockwell, W.; Taylor,
J.; Therrien, R.; White, S.; Brink, P.; Cabrera, B.; Clarke, R.;
Davies, A.; Dougherty, B. L.; Hennesy, M.; Irwin, K. D.; Nam, S.;
Penn, M. J.; Akerib, D.; Perera, T. A.; Schnee, R. W.; Young, B. A.;
Bauer, D.; Caldwell, D. O.; Hale, D.; Sonnenachein, A.; Yellin, S.;
Novikov, K.; Kusminov, V.
1997dmap.conf..445J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Quiet Sun HEL 1083 NM Chromospheric Flows
Authors: Penn, M. J.
1997ESASP.404..583P Altcode: 1997cswn.conf..583P
No abstract at ADS
---------------------------------------------------------
Title: Progress of the Cryogenic Dark Matter Search (CDMS) experiment
Authors: Shutt, T.; Akerib, D. S.; Barnes, P. D., Jr.; Bauer, D.;
Brink, P.; Cabrera, B.; Caldwell, D. O.; Chugg, B.; Clarke, R. M.;
Dasilva, A.; Davies, A.; Dougherty, B. L.; Emes, J.; Gaitskell, R. J.;
Golwala, S. R.; Hale, D.; Haller, E. E.; Irwin, K. D.; Knowlton,
W. B.; Kuzminov, V.; Lu, A.; Muno, M.; Nam, S. W.; Novikov, V.;
Penn, M. J.; Ross, R. R.; Sadoulet, B.; Seitz, D.; Smith, A.; Smith,
G.; Sonnenschein, A.; Stockwell, W.; Taylor, J. D.; Therrien, R.;
Trumbull, T. L.; White, S.; Yellin, S.; Young, B. A.
1996NuPhS..51..318S Altcode:
We report on progress of the CDMS experiment, which seeks to detect WIMP
dark matter through its interactions in a particle detector operated
in a low radioactivity environment. We have developed novel cryogenic
detectors which discriminate between nuclear recoils from WIMPs and
electron recoils from background photons. We describe the experiment
and discuss recent progress, including first operation of a cryogenic
detector in the low radioactivity cryostat in June of 1996.
---------------------------------------------------------
Title: Limb Observations of HE I 1083 NM
Authors: Penn, M. J.; Jones, H. P.
1996SoPh..168...19P Altcode:
Imaging spectroscopic data of the He I 1083 nm limb emission were
taken on several dates in October and November 1995 with the NASA/NSO
spectromagnetograph at the NSO/Kitt Peak vacuum telescope and on 9
December, 1993 with the Michigan infrared camera at the NSO/Sacramento
Peak vacuum tower telescope. Emission line profiles were observed in
quiet-Sun and coronal hole locations on the northern and southern solar
poles and on the east solar limb. The height of the He I 1083 nm shell
above the continuum limb at 1083 nm was measured to be 2.11 ± 0.12
Mm with the Kitt Peak data, and 1.74 ± 0.05 Mm with the Sacramento
Peak data. The Kitt Peak data show (1) within the measurement error
there is no significant difference in the height or thickness of
the emission shell in coronal holes compared with the quiet Sun,
(2) the 1083 nm emission intensity drops by 50% in coronal holes,
(3) the line width decreases by about 2 km s<SUP>-1</SUP> in coronal
holes (suggesting less inclined spicules), (4) the line width of the
He I 1083 nm line jumps significantly as the line of sight crosses the
solar limb (consistent with a higher temperature upper shell), (5) a
quiescent prominence shows a smaller spectral line width (consistent
with a cooler temperature or less velocity broadening), and (6) the
entire emission shell and the prominence show a He I spectral component
ratio of about 8 (suggesting optically thin emission).
---------------------------------------------------------
Title: He i 10830 Angstrom Wing Asymmetry in Polar Coronal Holes:
Evidence for Radial Outflows
Authors: Dupree, A. K.; Penn, M. J.; Jones, H. P.
1996ApJ...467L.121D Altcode:
Imaging spectroscopy of the Sun, carried out across the the solar
poles, yielded several thousand profiles of the He I 10830 A
chromospheric absorption line with effective spatial pixels of 1.1
x 2 arcsec2. Profiles of He I 10830 A show the relative blue-wing
absorption is stronger in the coronal holes than in the quiet Sun,
creating an asymmetric profile indicative of mass outflow. Within the
coronal holes, blueshifted line wings are found where He I absorption
is weak, corresponding to the center of supergranular cells. However,
in the quiet Sun, there is no line wing shift in supergranular
centers. Spatially compact regions of strong red-wing absorption also
occur across the disk. Within the polar coronal holes, the amplitude
of the wing shift shows a linear dependence with cos theta (where the
angle theta is measured with respect to an outward normal to the Sun's
surface), suggesting that a radial outflow occurs with a characteristic
speed of ~8 km s-1. These observations represent the first detection of
systematic outflows near the chromosphere transition region interface
that appear to mark the origin of the high-speed wind acceleration
from the solar surface.
---------------------------------------------------------
Title: He I 10830 Angstroms Polarimetry of Filament
Authors: Lin, H.; Kuhn, J. R.; Penn, M.
1996AAS...188.8001L Altcode: 1996BAAS...28..956L
Full Stokes parameters (IQUV) were obtained from a filament at the He
I 10830 Angstroms wavelength. These observations provide information
on the vector magnetic field configuration of the filaments, which,
up-to-date, were mostly infered from indirect observations like
the photospheric magnetograms and Hα images. We will present the
instrumentation, as well as the magnetic field configuration of the
filament derived from these data, and discuss their implications to
filament models.
---------------------------------------------------------
Title: Limb Observations of He I 1083nm
Authors: Penn, M.; Jones, H.
1996AAS...188.7906P Altcode: 1996BAAS...28..956P
Imaging spectroscopic data of the He I 1083 nm limb emission
were taken on several dates in Oct and Nov 1995 with the NASA/NSO
Spectromagnetograph at the NSO/Kitt Peak Vacuum Telescope and on 09 Dec
1993 with the Michigan Infrared Camera at the NSO/Sac Peak Vacuum Tower
Telescope. Emission line profiles were observed in quiet Sun and coronal
hole locations on the northern and southern solar poles and on the east
solar limb. The height of the He I 1083 nm shell above the continuum
limb at 1083 nm was measured to be 2.11+/-0.12 Mm with the Kitt Peak
data, and 1.74+/-0.05 Mm with the Sac Peak data. The Kitt Peak data show
(1) within the measurement error there is no significant difference in
the height or thickness of the emission shell in coronal holes compared
with the quiet Sun, (2) the 1083 nm emission intensity drops by 50%
in coronal holes, (3) the line width decreases by about 2 km s(-1) in
coronal holes (suggesting less inclined spicules), (4) the line width
of the He I 1083 nm line jumps significantly as the line-of-sight
crosses the solar limb (consistent with a higher temperature upper
shell), (5) a quiescent prominence shows a smaller spectral line width
(consistent with a cooler temperature or less velocity broadening), and
(6) the entire emission shell and the prominence show a He I spectral
component ratio of about 8 (suggesting optically thin emission).
---------------------------------------------------------
Title: Installation of the Cryogenic Dark Matter Search (CDMS)
Authors: Barnes, P. D.; da Silva, A.; Akerib, D. S.; Bauer, D.;
Brink, P.; Cabrera, B.; Caldwell, D. O.; Chugg, B.; Clarke, R. M.;
Cummings, A.; Davies, A.; Diaz, R. C.; Dougherty, B. L.; Emes, J.;
Golwala, S. R.; Hale, D.; Haller, E. E.; Irwin, K. D.; Knowlton,
W. B.; Kuziminov, V.; Lu, A.; Nam, S. W.; Penn, M. J.; Novikov, V.;
Pritychenko, B. V.; Quéinnec, F.; Ross, R. R.; Sadoulet, B.; Seitz,
D.; Shutt, T.; Smith, A.; Smith, G.; Sonnenschein, A.; Stockwell,
W.; Taylor, J. D.; Therrien, R.; Trumbull, T. L.; White, S.; Wolgast,
R. C.; Yellin, S.; Young, B. A.
1996NIMPA.370..233B Altcode:
We discuss the status of a cryogenic dark matter search beginning
operation in the Standard Underground Facility. The detectors will
be cooled in a specially designed cryostat connected to a modified
side access Oxford 400 dilution refrigerator. We discuss two detector
designs and performance, the cryostat construction and operation,
and the multi-level shield surrounding the cryostat. Finally, we will
examine the limits which we will be able to set on WIMP dark matter
with this experiment.
---------------------------------------------------------
Title: The Near-Infrared Coronal Spectrum
Authors: Kuhn, J. R.; Penn, M. J.; Mann, I.
1996ApJ...456L..67K Altcode:
Sensitive measurements of the near-infrared coronal spectrum were
obtained from the 1994 total solar eclipse. A new [S IX] emission line
at 1.25249 +/- 0.00003 mu m has been detected, and a bright, potentially
important diagnostic, [Si X] line at 1.43 mu m has been confirmed. Upper
limits on the intensity of several other predicted IR emission lines
have been established. Also, diffuse He I emission, perhaps geocoronal,
has been observed with a significant heliocentric redshift.
---------------------------------------------------------
Title: Infrared Spectroscopic Observations of Neutral Helium during
the 1994 Eclipse
Authors: Mann, I.; Kuhn, J. R.; Penn, M. J.
1996ASPC..104..345M Altcode: 1996pcdi.conf..345M; 1996IAUCo.150..345M
No abstract at ADS
---------------------------------------------------------
Title: Mapping Prominence Magnetic Fields: New He I 1083 nm Data
Authors: Penn, M.; Kuhn, J.
1995SPD....26..618P Altcode: 1995BAAS...27..965P
No abstract at ADS
---------------------------------------------------------
Title: Imaging Spectropolarimetry of the He i 1083 Nanometer Line
in a Flaring Solar Active Region
Authors: Penn, M. J.; Kuhn, J. R.
1995ApJ...441L..51P Altcode:
Slit spectra, simultaneously measuring left and right circular
polarization of the solar spectrum at 1082.9 +/- 0.4 nm, were taken
using the National Solar Observatory (NSO) Vacuum Tower Telescope
(VTT) at Sacramento Peak with a 128 x 128 pixel HgCdTe IR camera. By
moving the slit the solar active region NOAA 7629 was scanned with a
cadence of 246 s from 1724 to 1902 UT on 1993 December 6. The region
was in the decay phase of a C9.7 flare. Intensity, velocity and
longitudinal magnetic field in both the Si I (photospheric) and He I
(chromospheric) lines are computed from fits to the line profiles
in left and right polarizations. Analysis of these quantities show:
(1) He I line emission in three decaying flare kernels, (2) Zeeman
splitting of the He I emission measuring the longitudinal magnetic
field inside the flare kernels; (3) dark He I active region filaments
avoid strong longitudinal chromospheric magnetic field, and an active
filament (with a transverse speed of 9 km/s) produces fluctuations
in the strength of the longitudinal magnetic fields, and (4) bipolar
moving magnetic features (MMFs) and emerging active region bipoles
(EARBs) are observed at photospheric but not chromospheric heights.
---------------------------------------------------------
Title: The Near Infrared Coronal Spectrum: Results from the 1994
Eclipse
Authors: Kuhn, J.; Penn, M.; Mann, I.
1995SPD....26..609K Altcode: 1995BAAS...27..963K
No abstract at ADS
---------------------------------------------------------
Title: Infrared tools for solar astrophysics: What's next?
Authors: Kuhn, Jeffrey R.; Penn, Matthew J.
1995itsa.conf.....K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Polarimetric IR Array Observations of a Flare
Authors: Penn, M. J.; Kuhn, J. R.
1995itsa.conf..393P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: New Observations of IR Coronal Emission Lines
Authors: Penn, M. J.
1995itsa.conf...69P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Near-Infrared Emission-Line and Continuum Observations from
the 1991 Eclipse
Authors: Penn, M. J.; Arnaud, J.; Mickey, D. L.; Labonte, B. J.
1994ApJ...436..368P Altcode:
We report observations made during the 1991 July 11 total solar eclipse
from the University of Hawaii 61 cm south telescope on the summit of
Mauna Kea, Hawaii. The eclipse observations entail CCD imaging of a
coronal region on the southeast limb of the Sun using four wavelength
channels isolated with narrowband interference filters. We obtain two
long exposure images in each channel including the continuum (lambda
= 10690 A), the two near-infrared (Fe XIII) emission lines (lambda =
10747, 10798 A), and the He I line (lambda = 10830 A). We calibrate the
images to the center-of-disk solar intensity. The (Fe XIII) images are
the first coronal images published from these emission lines. We find
significant structural differences between the line and continuum images
implying large temperature gradients in our small field of view. We
compute the line ratio of the two (Fe XIII) emission lines (R) and find
that the ratio is within the limits 1.2 greater than or = R greater
than or = 15.0. We examine the motion seen in the prominence structure
and find transverse velocities of up to about 30 km/s. Finally we see
no cold coronal emission to a limit of 2 x 10<SUP>-7</SUP> solar BETA.
---------------------------------------------------------
Title: Ground-based Detection of an Infrared [Si x] Coronal Emission
Line and Improved Wavelengths for the Infrared [Fe xiii] Emission
Lines
Authors: Penn, M. J.; Kuhn, J. R.
1994ApJ...434..807P Altcode:
The wavelength of an infrared (Si X) coronal emission line is measured
to be 1430.084 +/- 0.006 nm with a coronagraph of the National Solar
Observatory at Sacramento Peak (NSOINP). New measurements of the
infrared (Fe XIII) emission lines locate the central wavelengths at
1074.617 +/- 0.005 nm and 1079.783 +/- 0.006 nm. The slit-averaged line
center intensities were 4.5, 27.8, and 5.2 (in units of 10<SUP>-6</SUP>
B(solar)) for the 1430 nm, 1075 nm, and 1080 nm emission lines,
repectively. The spatial distribution of (Si X) emission is correlated
with the coronal electron density as determined from the (Fe XIII)
line ratio. Upper limits are set for coronal emission near 1266 nm
and 1523 nm.
---------------------------------------------------------
Title: Coronal electron density measurements using the near-ir
[Fe XIII] emission lines
Authors: Penn, M. J.; Kuhn, J. R.; Arnaud, J.; Mickey, D. L.; Labonte,
B. J.
1994SSRv...70..185P Altcode:
Observations made during the 1991 total solar eclipse and recent
observations from NSO/Sac Peak are discussed. The ground-based density
measurements will be complimentary to SOHO observations, particularly
SOHO electron density measurements.
---------------------------------------------------------
Title: Removing Instrumental Polarization from Infrared Solar
Polarimetric Observations
Authors: Kuhn, J. R.; Balasubramaniam, K. S.; Kopp, G.; Penn, M. J.;
Dombard, A. J.; Lin, H.
1994SoPh..153..143K Altcode:
Full Stokes polarimetry is obtained using the National Solar
Observatory Vacuum Tower Telescope at Sacramento Peak while observing
the magnetically sensitive infrared FeI line at wavelength of 1.56μ. A
technique is described which makes use of the high magnetic resolution
in this spectral range to remove instrumental polarization from observed
StokesQ, U, andV line profiles.
---------------------------------------------------------
Title: How bright is the [Si X] 1431 nm coronal emission line?
Authors: Penn, M. J.; Kuhn, J. R.
1994SoPh..151...51P Altcode:
Airborne eclipse observations of the [SiX] 1430.5 nm coronal emission
line are reviewed, and new ground-based out-of-eclipse coronagraph
observations obtained at NSO/Sacramento Peak are reported. We find that
the [SiX] 1430.5 nm coronal emission line brightness is less than 8
× 10<SUP>−6</SUP>B⊙ in small active region corona which showed
[FeXIII] 1074.7 nm emission (corrected for sky background) of about
20 × 10<SUP>−6</SUP>B⊙.
---------------------------------------------------------
Title: The Source of 5 Minute Period Photospheric Umbral Oscillations
Authors: Penn, M. J.; Labonte, B. J.
1993ApJ...415..383P Altcode:
We observed the oscillations in the umbrae of two sunspots, using the
MCCD imaging spectrograph at the Mees Solar Observatory on Haleakala,
Maui. We perform four spatial analyses of the umbral velocity and find
that (1) there is more power traveling toward the center of the umbrae
than leaving the center of the umbrae (this provides a direct measure
of the absorption of p-modes by the sunspot umbrae); (2) the umbral
oscillations display power in the same spatial and temporal frequency
band as the quiet-sun oscillations; (3) Fourier-Bessel analysis of
one umbra shows no obvious resonant frequencies which might represent
natural oscillation modes; and (4) the centers of the umbrae have
less rms velocity at high spatial wavenumber than the edges of the
umbrae. We conclude: (1) the photospheric umbral oscillations are driven
by a source external to the sunspot, the global p-mode oscillations;
(2) there are no resonant frequencies in the oscillations; and (3)
the absorption of acoustic waves occurs inside the umbrae.
---------------------------------------------------------
Title: Coronal Electron Density Measurements from the Total Solar
Eclipse of 11 July 1991
Authors: Penn, M. J.; Arnaud, J.; Mickey, D. L.; Labonte, B. J.
1993BAAS...25.1210P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Source of Five-Minute Period Photospheric Umbral
Oscillations
Authors: Penn, Matthew J.
1993PASP..105..443P Altcode:
Many types of velocity oscillations are observed in the umbrae and
penumbrae of sunspots. We describe a project aimed at determining the
source of one type of oscillation, the five-minute period photospheric
umbra oscillations. The project uses imaging spectroscopy of spot
umbrae, measuring the Doppler shift of pure umbral absorption lines to
study the temporal and spatial properties of these oscillations. The
Mees CCD (MCCD) instrument is an imaging spectroscopy device which uses
the 25-cm coronagraph telescope and the 3.0-m coude spectrograph at
Mees Solar Observatory (MSO) on Haleakala, Maui. The instrument works
with resolving power up to R ~ 200,000 with significant throughput from
lambda-3934 A (Ca II K) to lambda ~ 10,000 A. A fast guiding active
mirror stabilizes the image during observations. A rapidly writing
magnetic tape storage system allows observations to be recorded
at 256 kbytes s^-1. We observed the oscillations in the umbrae of
two sunspots using the MCCD imaging spectrograph. We observed the
Doppler shifts of 18 molecular lines in the umbrae for roughly 50
hours in each spot during the interval of 11 to 16 May 1991. We find
no simple correlation between the velocity measured with molecular
lines and the velocity measured using two iron lines. We remove solar
rotation, image drift, and interpolate all the data onto an even
time grid. We perform four spatial analyses of the umbral velocity
and find (1) there is more power traveling toward the center of
the umbrae than leaving the center of the umbrae (this provides a
direct measure of the absorption of p-modes by the sunspot umbrae)
(2) the umbral oscillations have spatial and temporal characteristics
indistinguishable from the quiet-sun oscillations, (3) a Fourier-Bessel
analysis shows no obvious resonant frequencies which might represent
natural oscillation modes of the sunspot umbrae, and (4) the centers of
the umbrae have less RMS velocity than the edge of the umbrae. >From
these analyses we conclude that the photospheric umbral oscillations
are driven by an external source and that source is the global p-mode
oscillations. (SECTION: Dissertation Abstracts)
---------------------------------------------------------
Title: The Source of Five-Minute Period Photospheric Umbral
Oscillations
Authors: Penn, Matthew James
1992PhDT.........4P Altcode: 1992PhDT.......172P
Many types of velocity oscillations are observed in the umbrae and
penumbrae of sunspots. We describe a project aimed at determining the
source of one type of oscillation, the five-minute period photospheric
umbra oscillations. The project uses imaging spectroscopy of spot
umbrae, measuring the Doppler shift of pure umbral absorption lines to
study the temporal and spatial properties of these oscillations. The
Mees CCD (MCCD) instrument is an imaging spectroscopy device which uses
the 25 cm coronagraph telescope and the 3.0 m coude spectrograph at
Mees Solar Observatory (MSO) on Haleakala, Maui. The instrument works
with resolving power up to R ~ 200,000 with significant throughput
from lambda3934 A (Ca II K) to lambda ~ 10000 A. A fast guiding active
mirror stabilizes the image during observations. A rapidly writing
magnetic tape storage system allows observations to be recorded at
256 kbytes s^{-1}. We observed the oscillations in the umbrae of two
sunspots using the MCCD imaging spectrograph. We observed the Doppler
shifts of 18 molecular lines in the umbrae for roughly 50 hours in
each spot during the interval of 11 to 16 May 1991. We find no simple
correlation between the velocity measured with molecular lines and
the velocity measured using two iron lines. We remove solar rotation,
image drift, and interpolate all the data onto an even time grid. We
perform four spatial analyses of the umbral velocity and find (1)
there is more power traveling toward the center of the umbrae than
leaving the center of the umbrae (this provides a direct measure
of the absorption of p-modes by the sunspot umbrae), (2) the umbral
oscillations have spatial and temporal characteristics indistinguishable
from the quiet-sun oscillations, (3) a Fourier-Bessel analysis shows no
obvious resonant frequencies which might represent natural oscillation
modes of the sunspot umbrae, and (4) the centers of the umbrae have
less RMS velocity than the edge of the umbrae. From these analyses we
conclude that the photospheric umbral oscillations are driven by an
external source and that source is the global p-mode oscillations.
---------------------------------------------------------
Title: Properties of 5 Minute Period Oscillations in Sunspot Umbrae
Authors: Penn, M. J.; Labonte, B. J.
1992AAS...180.0603P Altcode: 1992BAAS...24..736P
No abstract at ADS
---------------------------------------------------------
Title: The Mees CCD imaging spectrograph
Authors: Penn, Matthew J.; Mickey, Donald L.; Canfield, Richard C.;
Labonte, Barry J.
1991SoPh..135..163P Altcode:
The Mees CCD (MCCD) instrument is an imaging spectroscopy device which
uses the 25 cm coronagraph telescope and the 3.0 m Coudé spectrograph
at Mees Solar Observatory (MSO) on Haleakala, Maui. The instrument works
with resolving power up to R ≈ 200 000 with significant throughput
from λ3934 Å (CaII K) to λ ≈ 10 000 Å. A fast guiding active
mirror stabilizes the image during observations. A rapidly writing
magnetic tape storage system allows observations to be recorded
at 256 kbytes s<SUP>−1</SUP>. Currently, the MCCD is used for
imaging spectroscopy of solar flares at λ6563 Å (Hα), and velocity
measurements of umbral oscillations; future plans include emission
line studies of active region coronae, and photospheric studies of
solar oscillations.
---------------------------------------------------------
Title: Analysis of p-modes in a Sunspot Umbra
Authors: Penn, M.; Labonte, B.
1991BAAS...23.1049P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: H alpha Spectra of Dynamic Chromospheric Processes in Five
Well-observed X-Ray Flares
Authors: Canfield, Richard C.; Penn, Matthew J.; Wulser, Jean-Pierre;
Kiplinger, Alan L.
1990ApJ...363..318C Altcode:
Simultaneous H-alpha and hard X-ray (HXR) spectra were obtained for five
solar flares to determine the relationship of H-alpha profiles and the
nonthermal part of the flare represented by the hard X-ray burst. All
five flares exhibited impulsive-phase redshifted H-alpha in emission,
which was temporarily and spatially associated with intense HXR emission
and broad impulsive-phase H-alpha wings. A few small regions within
two flares showed a blueshifted H-alpha emission which appeared only
early in the impulsive phase and was temporally correlated with the
HXR emission but not with broad H-alpha wings. Finally, there were
both redshifted and blueshifted absorption spectra with properties
fully consistent with those known for erupting and untwisting filaments.
---------------------------------------------------------
Title: Capabilities of the MCCD System at Mees Solar Observatory
Authors: Penn, M. J.; Mickey, D. L.; Canfield, R. C.
1990BAAS...22..880P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Hα Flare Observations with the Mees CCD Imaging Spectrograph
Authors: Canfield, R. C.; Mickey, D. L.; Penn, M. J.; Wülser, J. -P.
1990BAAS...22..809C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Moat Flows Using Magnetic Tracers
Authors: Penn, M. J.; Labonte, B. J.
1988BAAS...20..680P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The excitation and damping of solar oscillations
Authors: Libbrecht, K. G.; Popp, B. D.; Kaufman, J. M.; Penn, M. J.
1986Natur.323..235L Altcode:
Present theories suggest two classes of excitation processes which
may be responsible for the observed amplitudes of solar p-mode
oscillations-self-excitation of the modes via an overstability mechanism
such as the K mechanism <SUP>2</SUP>, and stochastic excitation by
turbulent convection<SUP>2-4</SUP>. We now have data which stand in
support of the latter mechanism. Linear overstability calculations are
still ambiguous, because of the uncertainties involved in including
turbulent viscous damping of the modes. Nevertheless no calculation
predicts overstable f-modes, and these modes are observed on the
Sun. Furthermore no nonlinear damping mechanism has yet been proposed
which would limit the growth of overstable modes to their observed
amplitudes. Assuming the modes are stably damped, the theory of mode
excitation by convective turbulence now gives mode amplitudes that are
in agreement with observations<SUP>4</SUP>. In this letter we use data
from Big Bear Solar Observatory to compare theory and observation in
detail. In particular, our data show that the energy per oscillation
mode is nearly constant at low mode frequencies, and is approximately
independent of degree at low degrees. The total energy in all the
oscillation modes is estimated at ~10<SUP>34</SUP>erg.
