- David McKenzie
I will describe an iterative scheme to clean up image pairs, in an effort
to converge on a temperature map from a de-scattered image pair. It is
based on a modification of the programs SXT_SCATTER, SXT_PSF. There are
some drawbacks to this scheme, some serious, but also some good points.
The program is appropriate for special cases (like flare PFIs), but not
for generation of a general mission-long database. This scheme was
developed and applied in order to de-scatter images and reproduce the
coronal hole temperatures derived by Foley et al., and in an attempt to
find temps/EMs in the fan above a spiky arcade on the northeast limb.
I will also try to summarize Foley's process, for the sake of
understanding the steps that he used to reach a solution.
- Barry LaBonte
While observations of point sources are the ideal for accurate
measurement of an instrument's point-spread-function (PSF),
observations of a knife-edge can provide nearly the same information.
The solar limb provides such an edge (C. A. Lindsey and T. L. Roellig,
Astrophys., J., 375, 414, 1991).
If the optically thin solar corona were spatially uniform,
then the intensity jump at the limb
would be close to a factor of 2, limiting the dynamic range of a PSF
measurement. Using the maps of SXT intensity as a function of
solar radius, polar angle and time generated by J. Li, it is
easy to find times and places where bright coronal emission
beyond the limb drives the ratio a factor of 10 higher, permitting
a more accurate measurement. This method should work for both
the central core of the PSF, using Full-res PFI images, and
the scattering wing, using FFI images.
- Hugh Hudson
I've completed a survey of the flare observations obtained in our special
flare-mode scattering table. It turned out there were a lot, including a
quite compact X-class flare that I'm working on in detail The survey and
my evolving bonehead image-plane straightforward analysis of the
scattering all can be found on these
pages.
The "best flare yet", ie the one I'm starting on, is memorialized in
this nugget.
- Hugh Hudson
It is probably not directly relevant to the SXT image deconvolution, but
pointing jitter is definitely a part of temperature analysis from image
ratios. I've documented the use of the complete IRU sampling, together
with some analysis of the Masuda flare, and this material can be found on
http://isass1.solar.isas.jaxa.jp/~hudson/jitter/jitter.html
The conclusions basically conclude that the Siarkowski et al. analysis was
right, although we're still dubious about their method of aligning images
by direct correlation between different filters.
- Nariaki Nitta
I think that the most important accomplishment we could get from this
workshop is a much better understanding of the SXT PSF (including
the scattering wing) in a wavelength-dependent way. I would like to
know how the vast knowledge of the AXAF/Chandra mirrors compares with
the SXT flare-mode data. It is my hope that there will be only a small
number of formal talks and that we will spend most of the time
discussing how much we can improve our in-flight calibrations and what
software should be developed to reflect that. A related problem we may
be interested to see discussed is how to better correct vignetting.
- Jing Li
"The influence of SXT scattering lights on the study
of high latitude streamers"
Due to projection effect, the high latitude streamers
originated from active regions are visible above the limb
while the corresponding active regions are either at close
or far side of the sun. The scattering lights from the
active regions may affect the brightness of these streamers
when the active regions are visible. The comparison of the
streamers taken by SXT/AlMg above the limb may provide
quantitative
data of SXT scattering lights.
- Loren Acton
I will review and summarize the information on the SXT PSF and
scattering wings that has accumulated (mostly in showpix/calibration)
over the years. I will also present new analysis of scattering wings
from flare starburst analysis of selected full-frame flare observations.
- Piet Martens & Margarita Karovska
"Using Blind Iterative
Deconvolution to clean up SXT full disk flare images"
We are trying
to use the well-tested and normally effective method of Blind Iterative
Deconvolution (BID) to remove the far-wing background scatter from
over-exposed flare regions in full disk SXT images. Preliminary
results will be presented at the workshop.
- Takeo Kosugi, Hirohisa Hara, and Sachiko Akiyama
"A Conservative Approach to SXT Image Deconvolution for Temperature
Analysis of Faint Structures Surrounding Flare Cores"
A possibility of inflight calibration of the SXT PSF will be discussed.
Since we have no point-like sources in the SXT observations of solar
flares, there is no way to estimate the SXT PSF with any mathematical
completeness. This does not mean, however, that we have no chances to
calibrate it in a limited sense, i.e., if our target is to have a better
image than the raw data, it may be achievable. I'll propose one such a way
and discuss its possibility as well as limitation. Feasibility of the
method will be examined in the workshop.
- Tom Metcalf
I have an MEM deconvolution algorithm (sxt_image_deconvolve.pro) which is
online. It is a very simple minded approach to MEM, but it works
reasonalby well. I also have some insight into the fast pixon algorithm
which may be a very practical way to do a deconvolution for a large data
set. Finally, I'm interested in using eclipse data to get a better handle
on the PSF, but I don't have any scheme to do this. It might be an
interesting topic for discussion though.
- Your Name Here
Your abstract here.