Project: datamanagement
Issue DM-4906: Investigate astrometry warnings from processing raw DECam data
This ticket includes efforts to troubleshoot and improve processing DECam raw data in Jan 2016. Investigations of the warnings from solving astrometry led to DM-4805, DM-4859. This ticket also includes partial efforts in DM-4859. For validation, I ran {{processCcd.py}} with two visits of raw Stripe 82 DECam data with and without the changes in DM-4859 (using the first camera geometry fix, which is different from the final fix). The script {{validateDecam}} in {{validate_drp}} is used to check astrometric scatter of the sources between the two visits. Output plots are in the attachments. By fixing DM-4859, the median astrometric scatter (mag < 21) decreases from 31.3 mas to 26.1 mas. The number of matches between two visits increases from 56768 to 71265. Also attached are the ra/dec patches plots, using the {{showVisitSkyMap.py}} script from DM-4095. The two colors represent the two visits of calexp wcs. Southern CCDs had bad astrometric solutions before DM-4859. The validation results are consistent with the patches visualization.
Story points: 12