SXT Deconvolution Workshop: Abstracts

These are listed in no particular sequence, in the order that they are received by McKenzie. At some later time we will decide on an order of presentation.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Your Name Here
    Your abstract here.

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Last modified 11/11/2003, by David McKenzie