[vsnet-grb-info 8982] GRB 100305A: P60 Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10471
SUBJECT: GRB 100305A: P60 Observations
DATE:    10/03/05 10:48:37 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko at srl.caltech.edu>

S. B. Cenko (UC Berkeley) reports on behalf of a larger collaboration:

We have imaged the field of GRB100305A (Troja et al., GCN 10470) with the
automated Palomar 60-inch telescope.  Images were obtained in the Sloan
g', r', i', and z' filters beginning at 09:09 UT on 5 March 2010 (~ 3.5
minutes after the burst).

In coadded images, we find no sources inside the XRT error circle to the
following limits (calculated with respect several point sources in the
SDSS DR7 catalog):

Filter		Mid-point	t_burst		Exposure	Magnitude
-------------------------------------------------------------------------
r'		09:25		19.5 min	720.0		> 22.0
z'		09:27		21.7 min	420.0		> 20.5
i'		09:28		23.3 min	660.0		> 22.0

The lack of an optical afterglow candidate, together with the long
duration and lack of X-ray absorption in excess of the Galactic value
(Troja et al., GCN 10470), make GRB100305A a candidate high redshift
event.  We encourage additional follow-up at longer wavelengths.