[vsnet-grb-info 8089] GRB 090708: Early RAPTOR Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9624
SUBJECT: GRB 090708: Early RAPTOR Optical Limits
DATE:    09/07/08 20:31:21 GMT
FROM:    James Wren at LANL  <jwren at nis.lanl.gov>

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

The RAPTOR telescope system responded to Swift trigger
356776 (Krimm et al., GCN 9621) under good observing conditions.
A nearly full moon was above the horizon at the time of the
observations, limiting sensitivity.  Our narrow-field instruments
began observing the location at 03:39:05.87 UTC, 50.62 s after
the Swift trigger (6.9 s after receipt of GCN message).  The data
from our R-band filtered system was calibrated to the USNO-B1
catalog.  These data show no new source within the BAT error
circle (Palmer et al., GCN 9623) when compared to the DSS.  We
can put the following R-band (Cousins) limits on the emission:

t-mid(s)          exp(s)   mag    mag-err
[since trigger]
----------------------------------------------------
61.59             5.0      16.2   3 sigma limit
101.85           30.0      17.3   3 sigma limit