TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1557
SUBJECT: XRF 020903: R band observations
DATE:    02/09/29 21:36:32 GMT
FROM:    Andrew S. Fruchter at STScI  <fruchter@mindspring.com>

A. Fruchter, L. Strolger, B. Mobasher,  J. Rhoads,  A. Levan, I. Burud
(STScI),  A. Becker (Lucent) report for a larger collaboration:

We observed the field of  XRF 020903 on both September 3.1 and 9.1 (UT) using
the Mosaic imager on the CTIO 4-m telescope.  Images were taken in B, R and I
on the first night and in only R on the second.  An image subtraction
performed shortly after the second night showed no variability consistent with
that expected of a GRB/XRF.  

In light of the report of the possible discovery of a counterpart to this
object (GCN 1554) we have re-examined our data.    We find that the object
cited as the possible counterpart declined by approximately 0.2 mags in R
between our two epochs.   

Unfortunately, we do not have a reliable absolute calibration of the field at
this moment.  We expect that a better calibration and more complete analysis
will be available on a relatively short timescale.