Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 17590

GRB 150314A: Early RAPTOR Detection
2015-03-17T00:43:21Z (9 years ago)
James Wren at LANL <>
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis,
of Los Alamos National Laboratory report:

The RAPTOR network of robotic optical telescopes made observations of Swift
trigger 634795 (Hagen, et al., GCN 17573).  Our narrow-field instruments
located in Los Alamos, NM, USA, arrived on target at 04:55:20.83 UT, T+27.98
seconds after the BAT trigger time.  Our initial 5s exposure shows the
counterpart (Zheng, et al., GCN 17574) at an unfiltered magnitude of
13.11 +- 0.02.  The source fades steadily, reaching magnitude 15.87 +- 0.09
at T+180.38 s, in agreement with the KAIT lightcurve (Zheng, et al., GCN
17585).  We derive a power-law decay slope of -1.50 using 04:54:52.86 as
the BAT T0.  Our unfiltered magnitudes were calibrated to the USNO-B1 R-band

The optical counterpart is not detected in any of our persistent wide-field
monitors during the gamma-ray emitting interval.  Typical 3-sigma unfiltered
limiting magnitudes during this period were V~9.8 based on comparison to the
Tycho-2 V-band catalog.
Looking for U.S. government information and services? Visit