[vsnet-grb-info 2347] Recent GRB UBVRcIc field photometry

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4184
SUBJECT: Recent GRB UBVRcIc field photometry
DATE:    05/10/31 16:31:02 GMT
FROM:    Arne A. Henden at AAVSO  <arne at aavso.org>

A. Henden (AAVSO/USNO) reports on behalf of the USNO GRB Team:

We have acquired UBVRcIc 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.
We are using a new CCD, and so place an additional zeropoint
error of about 0.03mag that should be added in quadrature
to the errors reported in the files listed below.
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/grb050505.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb051021.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb051022.dat
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb051028.dat

Since these bursts had identified optical afterglows, we may
improve the photometric calibration on subsequent observing runs.
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.