TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1100
SUBJECT: GRB010921 field photometry
DATE:    01/09/22 18:08:47 GMT
FROM:    Arne A. Henden at USNO/USRA  <aah@nofs.navy.mil>

A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:

We have acquired UBVRcIc all-sky photometry for
an 11x11 arcmin field that covers the center of the
error box for GRB010921 (GCN 1096,1097) with the USNOFS 1.0-m telescope
on one photometric night.  Stars brighter than
V=13.5 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/grb010921.dat
The current photometry has a potential external zero-point
error of about two percent.  The astrometry in this file
is based on linear plate solutions with respect to USNO-A2.0.
The internal errors are less than 100mas.
Further calibration of this field will be performed if
an optical afterglow is identified.