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Proceedings Paper

Determination of the eROSITA mirror half energy width (HEW) with subpixel resolution
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Paper Abstract

The Point Spread Function (PSF) of the eROSITA miror modules is specified to have an on-axis Half Energy Width (HEW) of 15 arcsec. This is only slightly larger than the eROSITA pixel size of 75 microns, which corresponds to 9.6 arcsec at the PANTER test facility, where the PSF is being measured with a prototype of the eROSITA CCD. We have developed a fast algorithm which provides a substantially higher spatial resolution by utilizing the information contained in the charge ratios of split events. By applying this algorithm to measurements where the CCD is systematically shifted in subpixel increments (typically in a 12x12 pattern), we are able to achieve an effective resolution of ~2 arcsec for specific pixel patterns. This algorithm can also be used to compute the two dimensional probability distribution for detecting a photon from an incident point-like beam, for each combination of photon energy, low energy threshold, selected pixel patterns, and subpixel scan properties. These maps allow us to deconvolve the measured PSF and thus to minimize the influence of the spatial detector resolution on the determination of the eROSITA mirror HEW. After launch, the algorithm for improving the spatial resolution by reconstructing the subpixel position will also be applied to the science data.

Paper Details

Date Published: 17 September 2012
PDF: 22 pages
Proc. SPIE 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 844350 (17 September 2012); doi: 10.1117/12.926988
Show Author Affiliations
Konrad Dennerl, Max-Planck-Institut für extraterrestrische Physik (Germany)
Wolfgang Burkert, Max-Planck-Institut für extraterrestrische Physik (Germany)
Vadim Burwitz, Max-Planck-Institut für extraterrestrische Physik (Germany)
Michael Freyberg, Max-Planck-Institut für extraterrestrische Physik (Germany)
Peter Friedrich, Max-Planck-Institut für extraterrestrische Physik (Germany)
Gisela Hartner, Max-Planck-Institut für extraterrestrische Physik (Germany)

Published in SPIE Proceedings Vol. 8443:
Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray
Tadayuki Takahashi; Stephen S. Murray; Jan-Willem A. den Herder, Editor(s)

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