Image reconstruction and deconvolution techniques applied to ASCA data

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Abstract
The Advanced Satellite for Cosmology and Astrophysics, ASCA, is a joint Japanese-United State X-ray astrophysics observatory which was launched on February 20th 1993. The scientific payload comprises four identical grazing incidence X-ray mirrors complemented by two charge-coupled devices and two gas scintillation proportional counters as the focal plane detectors. This paper presents the latest work carried out to improve the quality of ASCA images using the Lucy-Richardson deconvolution method. The ability to resolve two point sources is studied under various conditions of separation, relative intensity, and signal-to- noise. The method is also tested with an extended source. The minimum separation which can be resolved is 30 arcseconds, corresponding approximately to the radius of the core of the PSF. There is also some advantage to be gained in the relative orientation of the sources. Sources of unequal intensity must be separated further in order to be resolved, for example, when one source is half the intensity of the other source the minimum separation is 45 arcseconds. A signal-to-noise ratio of 5(sigma) is the lower limit for resolving two sources of equal strength 30 arcseconds apart. Deconvolution of the simulated image of the supernova remnant CAS-A is successfully carried out and the resulting image has about one arcminute resolution, limited by the PSF core width.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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