GCN Circular 21438

A. Goldstein (USRA) reports on behalf of the GBM-LIGO Group:
L. Blackburn (CfA), M. S. Briggs (UAH), J. Broida (Carleton College), E.
Burns (NASA/GSFC), J. Camp (NASA/GSFC), T. Dal Canton (NASA/GSFC), N.
Christensen (Carleton College), V. Connaughton (USRA), R. Hamburg (UAH), C.
M. Hui (NASA/MSFC), P. Jenke (UAH), D. Kocevski (NASA/MSFC), N. Leroy
(LAL), T. Littenberg (NASA/MSFC), J. McEnery (NASA/GSFC), R. Preece (UAH),
J. Racusin (NASA/GSFC), P. Shawhan (UMD), K. Siellez (GATech), L. Singer
(NASA/GSFC), J. Veitch (Birmingham), P. Veres (UAH), C. Wilson-Hodge
(NASA/MSFC)

At the G296853 event time, GBM was taking data and viewing the entire
un-occulted sky approximately 67 degrees from Earth center (RA = 66.9, DEC
= +23.4), which includes 49% of the LIGO Bayestar probability map.

There was a single GBM on-board trigger within 1 hour after the event time.
However, this trigger was likely due to a terrestrial gamma-ray flash and
unrelated to the G296853 event. The untargeted ground-based search of GBM
data for short-duration GRBs (Briggs et al., in prep) found a
low-reliability short GRB candidate ~76 minutes after the G296853 event
time, although the localization of this candidate is entirely inconsistent
with the Bayestar map.

The targeted search of the GBM data ([1], [2]) also did not find a
significant gamma-ray signal. This search processes time scales of 0.256 to
8.192 s within 30 s of the LIGO event. No interesting gamma-ray candidate
was found within this time window.

Further analysis and upper limits will be reported later.

[1] L. Blackburn et al. 2015, ApjS 217, 8
[2] A. Goldstein et al. arXiv:1612.02395
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