[vsnet-grb-info 18674] INTEGRAL SPI-ACS and IBIS/Veto observation of IceCube-161103

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20122
SUBJECT: INTEGRAL SPI-ACS and IBIS/Veto observation of IceCube-161103
DATE:    16/11/04 09:03:37 GMT
FROM:    Volodymyr Savchenko at ISDC,U of Geneve  <savchenk at in2p3.fr>

V. Savchenko (APC, Paris, France) , C. Ferrigno (ISDC, University of
Geneva, CH), P. Ubertini, A. Bazzano, L. Natalucci (INAF IAPS-Roma,
Italy), S. Mereghetti (INAF IASF-Milano, Italy), P. Laurent (CEA,
Saclay, France), E. Kuulkers (ESAC/ESA, Madrid, Spain)

Using INTEGRAL SPI-ACS and IBIS/Veto we have performed a search for a
prompt gamma-ray counterpart of the cosmic neutrino candidate IceCube-161103 (GCN 20119).

At the time of the event (2016-11-03 09:07:31.12 UTC, hereafter T0),
INTEGRAL was operating in the nominal mode. The spacecraft was
pointing in the direction of GRS 1915+105, and the neutrino localization
was at an angle of 113 deg with respect to the pointing axis.
This orientation implies moderately suppressed response of both SPI-ACS
and IBIS/Veto, with the best limit provided by SPI-ACS for every considered
spectrum for the sources in the 90% PSF containment of IceCube localization.

The background within +/-300 seconds around the event was very stable.
However, 90 seconds after T0 INTEGRAL/SPI-ACS detected a short excess
in a single bin (50 ms), consistent with the properties of the excesses
produced in SPI-ACS by cosmic ray interactions.
Probability of a cosmic ray effect with these properties happening within
the given search time window is 25%.

We estimate a 3-sigma upper limit on the 75-2000 keV fluence of
4.6x10^-7 erg/cm^2 for a burst lasting less than 1 s with a
characteristic short GRB spectrum (an exponentially cut off power law
with alpha=-0.5 and Ep=500 keV) occurring at any time in the
interval +/-300 s around T0.

For a typical long GRB spectrum (Band function with alpha=-1, beta=-2.5,
and Ep=250 keV), the derived peak flux upper limit is ~4.3x10^-7 (1.1x10^-6)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

We also set an upper limit on the peak flux on 8 s time scale  with IBIS/Veto
at the level of 1.9x10^-6 erg/cm^2/s in 75-2000 keV energy range.

No pointed INTEGRAL observations of the location of IceCube-161103 have been
performed or planned.