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Paper: Improving Position Accuracy in Archived HST Images
Volume: 442, Astronomical Data Analysis Software and Systems XX (ADASSXX)
Page: 73
Authors: Dencheva, N.; Hack, W.; Droetboom, M.; Fruchter, A.; Greenfield, P.
Abstract: We present changes to the HST pipeline, which aim at increasing the astrometric accuracy of archived HST images through successive World Coordinate System (WCS) corrections. In addition, all distortion information and astrometric corrections are stored in the science files, decreasing the size of a typical HST archive request. These changes allow the development of a WCS based version of Multidrizzle and image alignment software. We have developed two software packages to support these changes: PyWCS and STWCS. PyWCS is a general purpose WCS library. STWCS extends PyWCS and defines an HST specific WCS object. This paper provides details on how various WCS conventions have been merged to create a unified comprehensive description of the WCS of HST imaging observations.
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