TITLE:   GCN CIRCULAR
NUMBER:  6324
SUBJECT: GRB 070419A: RAPTOR Detection of Early Emission
DATE:    07/04/19 23:42:20 GMT
FROM:    James Wren at LANL  <jwren@nis.lanl.gov>

J. Wren, W.T. Vestrand, P.R. Wozniak, R. White, J. Pergande
of Los Alamos National Laboratory report:
 
Our Raptor telescopes responded to Swift trigger 276205
(Stamatikos et al., GCN 6302) at 10:00:49.8 UT, 83.7 s after
the trigger and 7.8 s after receiving the GCN packet.  We detect
optical emission from the counterpart reported by the KAIT team
(Chornock et al., GCN 6304).  Our observations show that the
counterpart brightened from below magnitude 18.8 to 18.44 (+- .15)
at a mid-exposure time of 10:09:27.9 UT (60s duration).  The
counterpart then began a slow decline but remained detectable in
our images until we interrupted our observing sequence at
10:47:17 UT for Swift trigger 276212.  Our unfiltered images were
calibrated using the R-band magnitudes from the USNO B1.0 catalog.
 
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