GCN Circular 662

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.