TITLE:   GCN CIRCULAR
NUMBER:  12407
SUBJECT: GRB 110928A: RAPTOR Limits During Gamma-ray Emitting Interval
DATE:    11/09/28 21:11:25 GMT
FROM:    James Wren at LANL  <jwren@nis.lanl.gov>

J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis,
of Los Alamos National Laboratory report:

The RAPTOR network of robotic optical telescopes made observations of Swift
trigger 504215 (Hoversten et al., GCN 12394).  The burst location was within
the field of our wide-field monitors which began a 10 s integration of the
location at 01:51:33.0 UT, 1.2 s after the Swift trigger time and during the
gamma-ray emitting interval.  The next wide-field 10 s integration begins at
01:51:52.1 UT, and is also within the gamma-ray emitting interval.  Neither
image shows a counterpart at the Swift XRT location (Evans et al., GCN 12398)
to an unfiltered 3-sigma limiting magnitude of 10.1 based on comparison to
the Tycho-2 V-band.  Our narrow-field instruments began imaging at
01:52:40.2 UT, 68.4 s after the Swift trigger.  The initial 5 s exposures
show no counterpart to a 3-sigma limiting magnitude of 16.1 when compared to
the USNO-B1 R-band.  The following table gives a sample of our observations.
The start time is given as the seconds between the start of the exposure and
the initial Swift trigger time.

start(s)   exp(s)    mag limit
------------------------------
1.22       10.0      > 10.1
20.32      10.0      > 10.1
68.44       5.0      > 16.1
153.55     10.0      > 16.5
413.45     30.0      > 17.2