TITLE:   GCN CIRCULAR
NUMBER:  7568
SUBJECT: GRB 080330: RAPTOR detection of prompt optical flash
DATE:    08/04/07 20:55:40 GMT
FROM:    James Wren at LANL  <jwren@nis.lanl.gov>

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

Our RAPTOR telescopes responded to Swift trigger 308041
(Mao et al., GCN 7537) at 03:41:39.93 UTC, 23.1 seconds
after the trigger.  Our observations show an optical flash
(about 10 s duration) at T ~ 60 s that is simultaneous
with the fourth gamma-ray peak detected by that BAT
(Markwardt et al., GCN 7549).  Subsequently, we detect the
rise of an optical afterglow starting at T ~ 150 s that
levels off to a flat plateau at around T ~ 300 s and then
starts to rapidly decay after about T ~ 2000 s.  The
unfiltered measurements reported in the following table
are calibrated to the USNO-B1 R band.

t-mid(s)    exp(s)     mag     mag-err
-----------------------------------------
38.78       31.4      (18.3)   5 sigma limit
58.88       5.0       17.46    0.22
83.15       31.3      (18.4)   5 sigma limit
141.96      22.7      17.62    0.10
294.80      22.7      17.03    0.07
504.74      15.0      17.15    0.06