TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3836
SUBJECT: GRB 050820: Early RAPTOR detections
DATE:    05/08/20 18:49:51 GMT
FROM:    James Wren at LANL  <jwren@nis.lanl.gov>

J. Wren, W. T. Vestrand, P. Woznaik, S. Evans, R. White report
on behalf of the RAPTOR team at Los Alamos National Laboratory:

The RAPTOR system of robotic telescopes responded to GRB 050820
(Swift trigger 151207) beginning at 06:35:20.46 UT, 5.5 seconds
after the GCN notice was sent.  We detect the object reported by
Fox and Cenko (GCN 3029).  Our early images show the source
rising rapidly to a unfiltered peak magnitude of ~14.5.  We confirm
the Fox and Cenko observation that the source reaches
a peak brightness approximately 8 minutes after the burst and
then begins a steady power law decline.