The first makes use of a new version of the Hubble Guide Star Catalog (GSC version 2.4.0) which updates the coordinates of the guide stars with the positions from Gaia DR1. The World Coordinate System (WCS) in the image header of all WFC3 and ACS datasets were updated and may include one or more corrections. On December 3, 2019, the first set of improved astrometry data were released in MAST. We therefore recommend these to be used as ‘discovery images’ for comparing observations in different detectors and passbands and not for precise photometry. When combining observations over a large date range, MVMs may have photometric errors of several percent or systematic alignment errors when combining visits with different catalog solutions. The MVM data products combine all ACS/WFC, WFC3/UVIS, or WFC3/IR images falling within a pre-defined 0.2° x 0.2° 'sky cell' for each detector+filter, which are drizzled to a common all-sky pixel grid.
#STSCI ASTROMETRY ARCHIVE#
These catalogs supersede those produced by the Hubble Legacy Archive and will be the basis of the next version of the Hubble Source Catalog. The SVM products include an additional relative alignment across filters in a visit, and the drizzled images are used to generate point source and segment catalogs during pipeline processing. We describe two new types of Hubble Advanced Products (HAP), referred to as Single Visit Mosaics (SVMs) and Multi Visit Mosaics (MVM), which began production in MAST in late-2020 and mid-2022, respectively. We compute statistics on the alignment fraction for each detector and estimate the uncertainties in the WCS solutions when aligning to different reference catalogs.
The updated WCS solutions are computed during pipeline processing by aligning sources in the HST images to a select set of reference catalogs (e.g. This ISR describes updated WCS solutions in MAST data as well two new types of Hubble Advanced Products.Ībstract: As of late-2019, MAST data products for ACS and WFC3 include improved absolute astrometry in the image header World Coordinate System (WCS). In August 2022, a new ACS/WFC3 instrument science report ( ACS ISR 2022-03 WFC-06) titled ' Improved Absolute Astrometry for ACS and WFC3 Data Products' was published.
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