TITLE:   GCN CIRCULAR
NUMBER:  7386
SUBJECT: GRB 080310, SMARTS optical/IR afterglow observations
DATE:    08/03/10 09:48:46 GMT
FROM:    Bethany Cobb at Yale U  <cobb@astro.yale.edu>

B. E. Cobb, part of the larger SMARTS consortium, reports:

Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 080310
(GCN 7382, Cummings et al.) beginning 20 minutes post-burst
(2008-03-10 08:58 UT).  Total summed exposure times amounted
to 180s in BRIYJK and 120s in H and V.

The afterglow of GRB 080310 (GCN 7382, Cummings et al. & GCN 7383,
Chornock et al.) is detected in our images.  Preliminary comparison to
USNO-B1.0 stars in I and 2MASS stars in J indicates the following
afterglow magnitudes:

time post-burst         I mag           J mag
~25 minutes             16.3+/-0.2      15.9+/-0.2

The afterglow fades by ~0.4 magnitudes in I between 25 and 45 minutes
post-burst.  This source is therefore confirmed to
be the afterglow of GRB 080310, with a decay rate of alpha ~ -0.6.