[vsnet-grb-info 5924] GRB 080319A: Early RAPTOR optical limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7570
SUBJECT: GRB 080319A: Early RAPTOR optical limits
DATE:    08/04/08 20:42:18 GMT
FROM:    James Wren at LANL  <jwren at nis.lanl.gov>

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

Our RAPTOR telescopes imaged the location of Swift trigger
306754 (Pagani et al., GCN 7426).  We do not detect the optical
counterpart initially reported by Cenko et al. (GCN 7429).  The
location of the counterpart was within the field of view of our
continuous all-sky monitoring system.  We can place 5 sigma
limits at approximately magnitude 9.0 during the time period
within 5 minutes both before and after the trigger.  Our
narrow-field instruments began observing the location at
05:46:51.90 UTC, 69.8 s after the Swift trigger, but also did
not detect the counterpart.  The limiting magnitudes of our
unfiltered observations when calibrated to the USNO-B1 R-band
are given in the following table.

t-mid(s)    exp(s)     mag     mag-err
--------------------------------------------
-19.18      10.0       9.0     5 sigma limit
14.07       10.0       9.0     5 sigma limit
72.35        5.0      16.9     5 sigma limit
156.60      10.0      17.4     5 sigma limit
423.25      30.0      18.0     5 sigma limit