[vsnet-grb-info 564] GRB021112, BVRI field photometry

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1697
SUBJECT: GRB021112, BVRI field photometry
DATE:    02/11/19 02:56:54 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 shallow BVRcIc all-sky photometry for
a 20x20 arcmin field centered about 7arcmin north and 7 arcmin
west of the position of the variable source mentioned in
Strolger et al. (GCN1696), but within the error box for
GRB021112 (Fenimore et al.,GCN1682), using the USNOFS 1.0-m telescope
on one marginal night.  Stars brighter than V=13.0 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/grb021112.dat
The astrometry in this file is based on linear plate solutions
with respect to USNO-A2.0.

While the night was photometric, there was poor and variable
seeing due to a frontal passage.  We estimate the present zeropoint
errors to be about 0.03mag.  If the variable source is confirmed
to be the afterglow for GRB021112, we will extend the calibration
with additional nights to guard against a systematic zeropoint error.
You should check the dates on the .dat file prior to final publication
to get the latest photometry.

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