TITLE:   GCN CIRCULAR
NUMBER:  20742
SUBJECT: LIGO/Virgo G275404: Fermi GBM Observations
DATE:    17/02/26 00:59:37 GMT
FROM:    E. Burns at U of Alabama/Huntsville  <eb0016@uah.edu>

E. Burns (UAH) reports on behalf of the GBM-LIGO Group:
Lindy Blackburn (CfA), Michael S. Briggs (UAH), Jacob Broida (Carleton
College), Jordan Camp (NASA/GSFC), Tito Dal Canton (NASA/GSFC), Nelson
Christensen (Carleton College), Valerie Connaughton (USRA), Adam Goldstein
(USRA), Rachel Hamburg (UAH), C. Michelle Hui (NASA/MSFC), Pete Jenke
(UAH), Dan Kocevski (NASA/MSFC), Nicolas Leroy (LAL), Tyson Littenberg
(NASA/MSFC), Julie McEnery (NASA/GSFC), Rob Preece (UAH), Judith Racusin
(NASA/GSFC), Peter Shawhan (UMD), Karelle Siellez (GA Tech), Leo Singer
(NASA/GSFC), John Veitch (Birmingham), Peter Veres (UAH), Colleen
Wilson-Hodge (NASA/MSFC)

GBM was observing 81% of the LIGO probability map for G275404 at the
event time, with much of the northern high probability region and half of
the southern arc observed. There is no GBM
on-board trigger around the event time. The untargeted ground-based
search of GBM data for short-duration GRBs (Briggs et al., in prep) found
no candidates close in time to G275404.
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.

Any prompt gamma-ray burst emission, above the GBM detection threshold,
must have been occulted by the Earth for Fermi.  The Earth-occulted region
is a circle with radius of 68 degrees, centered on RA, Dec = 134.5, +25.6.

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