GCN Circular 3855
A. Henden (AAVSO/USNO) reports on behalf of the USNO GRB Team: We have acquired BVRcIc all-sky photometry for 23x23arcmin fields centered on the coordinates of recent GRB localizations with the USNOFS 1.0-m telescope on 1 or 2 photometric nights but with bright moonlight and variable seeing. 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/grb050525.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050607.dat ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb050802.dat The astrometry in these files is based on linear plate solutions with respect to UCAC2 or USNO-A2.0. The external errors are usually 200mas or better. The estimated external photometric error is about 0.03mag. Some fields are relatively crowded, and the large apertures required to handle the variable seeing also blended some measurements, so choose comparison stars wisely. We have one additional night for GRB050525 that will be added when reductions are complete. 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.