TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3454 SUBJECT: Recent GRB BVRcIc field photometry DATE: 05/05/22 21:17:55 GMT FROM: Arne A. Henden at AAVSO A. Henden (AAVSO/USNO) reports on behalf of the USNO GRB Team: We have acquired BVRcIc all-sky photometry for 11x11arcmin fields centered on the coordinates of recent GRB localizations with the USNOFS 1.0-m telescope on one photometric night but with bright moonlight. Stars brighter than V=12.0 are saturated and should be used with care. We have placed the photometric data on our anonymous ftp site: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050319.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050401.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050408.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050416.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050502a.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050509b.dat The astrometry in these files is based on linear plate solutions with respect to UCAC2. The external errors are less than 100mas. The estimated external photometric error is about 0.03mag. Since these bursts had identified optical afterglows, we expect to improve the photometric calibration on subsequent nights. As always, you should check the dates on the .dat file prior to final publication to get the latest photometry. There is a README file on the ftp directory to give you information about the procedures used to calibrate these fields.