TITLE:   GCN CIRCULAR
NUMBER:  6391
SUBJECT: GRB 070508, SMARTS optical afterglow observation
DATE:    07/05/08 21:34:04 GMT
FROM:    Bethany Cobb at Yale U  <cobb@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 imaging of the error region of GRB 070508
(GCN 6383, Grupe et al.) with a mid-exposure time of
2007-05-08 06:25 UT (~2.1 hrs post-burst).  The total summed exposure
time amounted to 36 minutes in I.

A source is detected at the UVOT afterglow coordinates (GRB 6383, Grupe et 
al.) with a magnitude of I=20.7+/-0.3, calibrated using USNO-B1.0 values.