TITLE: GCN GRB OBSERVATION REPORT NUMBER: 662 SUBJECT: GRB000418, UBVRI field photometry update DATE: 00/05/03 18:16:03 GMT FROM: Arne A. Henden at USNO/USRA A. Henden (USRA/USNO) reports on behalf of the USNO GRB team: Final UBVRcIc all-sky photometry for the field of GRB000418 is now available on our anonymous ftp site: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb000418.dat It has been acquired with the USNOFS 1.0-m telescope on three photometric nights. This 11x11arcmin field surrounds the proposed counterpart and extends a little fainter than V=21. All stars brighter than V=14 are saturated and should be used with care. The astrometry in this file is based on linear plate solutions with respect to USNO-A2.0. The internal errors are less than 100mas. The field is filled with galaxies. In fact, object C in the original list of comparison stars is a galaxy; it has been replaced in the updated table below with a stellar object (G) to the north of the optical counterpart: ID x y U B V R I A 000 000 16.718 16.668 16.020 15.654 15.291 0.020 0.020 0.019 0.019 0.019 B -158 +050 19.559 18.529 17.447 16.802 16.281 0.192 0.030 0.027 0.027 0.027 D -094 -006 - 20.424 19.631 19.118 18.538 0.051 0.032 0.035 0.070 E -200 -042 - 19.856 18.988 18.484 18.043 0.021 0.021 0.061 0.078 G -102 +220 19.402 19.800 19.330 18.935 18.637 0.150 0.065 0.065 0.065 0.079 Notes: star A is the Mirabal et. al. comparison star; x,y offsets are in arcsec with respect to this star, positive east and north.