[vsnet-grb-info 4060] GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5873
SUBJECT: GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
DATE:    06/11/27 20:48:42 GMT
FROM:    James Wren at LANL  <jwren at nis.lanl.gov>

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

Our autonomous Raptor-S telescope responded to Swift trigger
240766 (Sbarufatti et al. GCN 5854) at 08:48:17.29 UT, 20.87 s
after the trigger and 4.3 s after receiving the GCN packet.
Our first two images were obtained while the Swift BAT was still
detecting emission from the GRB.  We clearly detect a fading
optical source at the location of the optical counterpart seen
by the UVOT (Vanden Berk et al. GCN 5856).  Our measurements
show that the optical counterpart faded from magnitude R=12.3
to 14.4 over the first 90 seconds.  Our unfiltered magnitudes
were calibrated using the R-band magnitudes from the USNO B1.0
catalog.