[vsnet-grb-info 2799] GRB 060202: Optical Afterglow Candidate from Keck/LRIS

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4636
SUBJECT: GRB 060202: Optical Afterglow Candidate from Keck/LRIS
DATE:    06/02/03 09:23:20 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko at srl.caltech.edu>

S. B. Cenko, D.-S. Moon, (Caltech), and B. P. Schmidt (MSO-ANU) report on
behalf of a larger collaboration:

We have imaged the field GRB060202 (Fox et al., GCN 4629) with the
Low-Resolution Imaging Spectrometer mounted on the 10-m Keck I telescope.
Observations consisted of 2 x 300 s images taken simultaneously in the
g and I filters at a mean time of approximately February 3.22.  Images
were taken under good seeing conditions, though shortly after sunset with
a high background.

Inside the revised XRT error circle (Morris et al., GCN 4632), we find one
faint source (S1) in our I-band images detected at approximately the
2-sigma level.  The location of this source is (J2000):

	RA: 02:23:22.88
	Dec: +38:23:04.3

with an approximate error of 1.0" in each coordinate.  The magnitude of
this object, with reference to the USNO-B2 catalog, is approximately I =
22.6 +/- 0.3, with photometric calibration dominating the errors.  We find
no source in our g-band coadd at this location to a limiting magnitude of
approximately g > 22.0.  We note this position is consistent with the
detection of a K-band source with UKIRT by Wang et al. (private
communication, GCN forthcoming).

There is one additional source (S2), of similar magnitude and color,
located just outside the edge of the XRT error circle, which we include
for completeness.  The location of this source (J2000.0) is:

	RA: 02:23:22.80
	Dec: +38:23:08.9

While we cannot comment on variability at this time, we propose that the
source S1 is the afterglow of GRB 060202.

The early R-band limits provided by Monfardini et al. (GCN 4630) indicate
a red R-I color for this potential afterglow.  Given the possibility that
this object is at high redshift (z > 5), we have triggered Gemini NIR
imaging of the field.  A report on these observations will follow in
a subsequent GCN.