[vsnet-grb-info 5336] GRB 071030, SMARTS afterglow observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7024
SUBJECT: GRB 071030, SMARTS afterglow observations
DATE:    07/10/31 03:21:10 GMT
FROM:    Bethany Cobb at Yale U  <cobb at astro.yale.edu>

B. E. Cobb (Yale), 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 071030
(GCN 7020, Stroh et al.), with a mid-exposure time of
2007-10-31 01:46 UT, which is ~40 minutes post-burst.
Several dithered images were obtained in each filter,
with total summed exposure times of 180s in each of BRIYJK and
120s in each of H and V.

The GRB afterglow (GCN 7020, Stroh et al. & GCN 7021, Kruehler et al.)
is detected at I=17.4+/-0.1 (Photometry is calibrated against USNO-B1.0
stars).  Additional imaging at 1.5 hours post-burst indicates an 
approximate decay rate of alpha~-0.6 (where afterglow flux is proportional
to t^alpha).