TITLE:   GCN CIRCULAR
NUMBER:  18352
SUBJECT: ANTARES neutrino detection: Fermi GBM Observations
DATE:    15/09/21 13:07:07 GMT
FROM:    Valerie Connaughton at UAH/NSSTC  <valerie.connaughton@nasa.gov>

Lindy Blackburn (CfA), Michael S. Briggs (UAH), Eric Burns (UAH), Jordan Camp
  (NASA/GSFC), Nelson Christensen (Carleton College), Valerie Connaughton (USRA),
Adam Goldstein (NASA/MSFC), Peter Jenke (UAH), Tyson Littenberg (UAH),
  Judith Racusin (NASA/GSFC), Peter Shawhan (UMD), Leo Singer (NASA/GSFC),
John Veitch (Birmingham), Colleen Wilson-Hodge (NASA/MSFC), and Binbin Zhang (UAH)

  On September 1st, 2015, at 07:38:25 UT, the time of the reported neutrino
detection by ANTARES (Dornic et al., GCN 18231), Fermi GBM was observing the
reported neutrino position with several GBM detectors having a good geometry to the
source.

We searched for associated gamma-ray emission with 3 different search techniques.

A seeded search for impulsive emission around the time and sky location of the
detected neutrino yielded no candidates above the GBM background.  The search
method was developed to look for electromagnetic counterparts in the GBM data of
sub-threshold gravitational wave signals found in the LIGO data (Blackburn et al.
2015, ApJS, 217, 8), and implemented here in a 60 s search window centered on the
time and seeded with the position of the detected neutrino.

A blind search for untriggered impulsive emission in the GBM data in the 11 hours
centered on the neutrino detection yielded no candidates consistent with the
position of the neutrino.  This search technique was developed for the detection of
untriggered short GRBs in the GBM data, and is also sensitive to long GRBs and
other transients up to about 100 s in duration (Zhang et al., in preparation).

Measurements using the Earth Occultation technique of the flux from the Swift XRT
source reported within the ANTARES error box by Dornic et al. in the 24 period
after the neutrino detection place a flux limit of 150 mCrab between 12 and 300 keV.