Participants:
Takeo Kosugi Hiro Hara Piet Martens Hugh Hudson David McKenzie Loren Acton Tom Metcalf Phil Shirts Nariaki Nitta Leon vanSpeybroeck Barry LaBonte Jing Li Agenda: Thursday, 1/18/01 AM Discussions of Point Spread Function. PM Discussion of deconvolution techniques. Friday, 1/19/01 Work by participants. Summary session at 16:00.
Scattering Wings: McKenzie, Metcalf and Shirts performed experiments using FFT and MEM techniques to clean an SSC with a PSF comprising a delta-function core and scattering wings which fall of as the square of the distance form the scattering source. Initial efforts were encouraging. Acton verified the slope of the SXT scattering wings in sxt_psf.pro (-1.89) by normalizing the PSF to one location in a 12/26/91 starburst image and subtracting that PSF from the starburst. The correction was satisfactory. Residual noise in the corrected image centered on 0.
Flare correction: Hudson examined recent data from the flare scattering table experiment that traced the shadow of the entrance-filter "spider" to near the core of the flare. Kosugi and Hara were successful in their attempts to clean a flare image through the use of FFT with "bandwidth expansion" (rebinning to finer pixels by a factor of 2) employing a Gaussian weighted Moffat function for the core PSF. The elimination of the broad wings of the Moffat function stabilized the deconvolution.
Other: Martens investigated blind iterative deconvolution (BID) and concluded that this technique, which yields both a cleaned image and a PSF, is worth pursuing as a means of better determining the SXT PSF with partial-frame images. LaBonte demonstrated that when placing the FFI into a larger array to do an FFT it is not necessary to take into account the scattering into the extended image -- zeroes are OK. Also, when deconvolving half-resolution FFIs it is not necessary to expand the bandwidth by rebinning to mroe pixels.