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1995 Summer Student Program (1Sep95)
(from NSO, NOAO Newsletter No. 43, September 1995)

Robert Cameron (University of Sydney) is working with Ray Smartt on
two solar topics. The first is the morphology of coronal loop
interactions, especially in Ha, using high-resolution coronagraph
images from the Evans Facility. The second topic involves analyzing
Fabry-Perot observations that were obtained at the November 1994
eclipse in Chile by Jim Mason. The locations of the circular
interference fringes superimposed on the coronal field are used to
deduce velocities in the corona.

Enrique Chavez (University of Arizona) is working with Mark Giampapa
and Dave Jaksha on a project to evaluate the performance of the
McMath-Pierce stellar spectrograph with different transfer optics and
gratings. The measurements are made using three lines (393.3, 589.5
and 656.3 nm) from a thorium-argon lamp. The line profiles can be used
for comparison and calibration of stellar spectra.

Dali Georgobiani (Abastumani Astrophysical Obs.) is working with Jeff
Kuhn on two problems. Her first task is to devise an algorithm in
spatial frequency space which speeds up the computational speed of the
Kuhn et al. algorithm used for precise flat-fielding of image array
data; this is needed for the RISE/PSPT program. Georgobiani has also
begun a calculation to understand how a non-spherical solar interior
temperature distribution could affect the neutrino flux as measured by
the Homestake, gallium, and Kamiokande detectors.

Mark Haun (Walla Walla College) is working with Bill Livingston on the
evaluation of telescope seeing at the McMath-Pierce. He has
constructed and tested a stellar-image motion analyzer. He is also
looking into an active optics system for the 2-meter heliostat.

Kelsey Johnson (Carleton College) is working with Harrison Jones on
the analysis of solar magnetogram sequences. Using a dynamical
technique called multiscale regularization, she obtains flow maps for
consecutive magnetograms spaced closely in time. These flow maps are
examined for correlations with specific solar events.

Sean Matt (University of Arizona) is working with Donald Neidig on the
analysis of coronal sky background images to determine the power
spectrum and origin of background noise.  He is also studying flare
Moreton waves in an effort to better understand the link between
flares and coronal mass ejections. Additional objectives of the latter
project include studies of post-flare loops and the search for recent
examples of the flare nimbus phenomenon.

Nadege Meunier (University of Paris) is working with Stuart Jefferies,
developing a two-dimensional fitting algorithm designed to
characterize the solar l-n spectra of solar oscillations. Model
parameters determined by 2-D fitting are expected to have much
improved error estimates over those from 1-D fitting. In addition, the
fits can be accomplished with many fewer parameters, which should lead
to more robust modeling at high temporal and spatial frequencies.

Elena Neagu (Western Ontario University) is working with Frank Hill on
a project to determine how mode leakage caused by observational
constraints affects the analysis of GONG data. The most important
observational constraints are GONG's inability to see the entire solar
surface and the limitations of discrete sampling using rectangular
pixels.

Stefan Ploner (ETH Zurich) is working with Steve Keil and K.S.
Balasubramaniam on modeling Stokes spectral line profile asymmetries
in the presence of velocity and velocity gradients. Earlier work by
Balasubramaniam, Keil and Steve Tomczyk (HAO), using Stokes profiles
observed with the HAO/NSO Advanced Stokes Polarimeter (ASP), showed
that both velocities and velocity gradients are clearly related to the
Stokes profile amplitude asymmetries in active regions. Ploner will
synthesize spectral line profiles from polarized radiative transfer
calculations, using the observational vector magnetic field and
velocity data from the ASP, and compare them with the observed
spectral line profiles. This will help in a better understanding of
the Stokes spectral line asymmetries as a diagnostic tool.

Robert Quinn (University of Arkansas, Fayetteville) is working with
Jack Zirker analyzing a time series of Calcium K-line images obtained
at the South Pole in 1994/95 with the High-l helioseismometer. The
data span 16 days continuously at a cadence of 42 seconds. The goal of
the investigation is a search for large-scale persistent flows with a
scale of about one arcminute. Quinn was new to IDL at the beginning of
the summer but is an expert now! Preliminary results on solar flows
are expected before the end of the summer.

Seth Redfield (Tufts University) is working with Charles Lindsey, Doug
Braun, Stuart Jefferies and Yeming Gu with the NSO-NASA-Bartol South
Pole observations of 1987/88/90 on a project in local helioseismology.
Seth has written and tested software that is being used to look for
antipodal color images: acoustic deficits expected at the antipodes of
far-side sunspots due to waves absorbed by the sunspots. He is also
working on techniques for correcting solar images for flat-field
errors using solar rotation.

Reed Riddle (Georgia State University) is working with Stuart
Jefferies, modeling the individual m-n spectra for the NSO-NASA-Bartol
South Pole data sets. He is updating NSO's decade-old
maximum-likelihood algorithm to include the many advances in modeling
that have been made since the code was written. Riddle will invert the
results to obtain rotational profiles of the solar interior for each
of the data sets.

Jeffrey Selden (New Mexico State University) is working with Haosheng
Lin and the RISE team on the digitization and calibration of Ca K
spectroheliograms collected daily for more than thirty years at the
NSO/SP Evans Facility. The Ca K SHG archive is of special interest to
researchers interested in the solar irradiance variations. By
decomposing the Ca K SHG into different components (plages, networks,
quiet sun, etc.), we hope to better understand the underlying physical
processes that are responsible for the observed cyclic total solar
irradiance variations. Selden has been working on a self-consistent
method for calibrating photographic SHGs that have a poor or missing
calibration at the time of observations.

Michael Sigwarth (Kiepenheuer-Institut f�r Sonnenphysik) is working
with K.S. Balasubramaniam and Steve Keil on the problem of finding
vector magnetic field signatures of foot-points in solar prominences.
It is unclear how these giant arches of gas are tethered to the
photosphere. Sigwarth will work on data from the HAO/NSO Advanced
Stokes Polarimeter (ASP) in an effort to identify the vector magnetic
signature of the prominence foot-points. Solar prominences often
detach, resulting in mass ejections that have consequences on
near-Earth space and the terrestrial environment. This work will help
identify the physical mechanisms that are involved in the stability of
prominences.

Amy Winebarger (King College) is working with Stuart Jefferies
modeling the solar l-v power spectra of solar oscillations observed
from the NSO-NASA-Bartol South Pole observations. She is looking for
variations of the model parameters over the solar cycle. Winebarger
will compare the frequency differences with the measurements made by
the Big Bear group and will also determine whether the mode line
widths are changing with solar cycle.

K.S. Balasubramaniam, Mark Giampapa,
Stuart Jefferies,Harry Jones, Steve Keil, Jeff Kuhn,
Haosheng Lin, Charles Lindsey, Bill Livingston,
Don Neidig, Ray Smartt, Jack Zirker

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