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GCN Circular 26666

IceCube-200107A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
2020-01-08T11:28:39Z (4 years ago)
Alexis Coleiro at APC/U. Paris Diderot <>
Alexis Coleiro (APC, France), Carlo Ferrigno (ISDC/UniGE, Switzerland),
V. Savchenko (ISDC/UniGE, Switzerland),
J. Rodi (IAPS-Roma, Italy),
S. Mereghetti (INAF IASF-Milano, Italy)
on behalf of the INTEGRAL multi-messenger collaboration:

Using INTEGRAL/SPI-ACS realtime data (following [1]) we have performed
a search for a prompt gamma-ray counterpart of IceCube-200107A (GCN 26655).
At the time of the event (2020-01-07 09:42:18 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 78 deg with respect to the
spacecraft pointing axis. This orientation implies strongly suppressed
(24% of optimal) response of ISGRI, strongly suppressed (40% of
optimal) response of IBIS/Veto, and near-optimal (70% of optimal)
response of SPI-ACS.
The background within +/-300 seconds around the event was somewhat
unstable (excess variance 1.8).
We have performed a search for any impulsive events in INTEGRAL SPI-
ACS (as described in [2]) data (IBIS data are not considered since they are 
only partially available in the search region due to the instrument starting the 
observations after the perigee shortly before the IceCube trigger).
We do not detect any significant counterparts and estimate a 3-sigma
upper limit on the 75-2000 keV fluence of 2.8e-07 erg/cm^2 (within the
50% probability containment region of the source localization) 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=600 keV)
occurring at any time in the interval within 300 s around T0. For a
typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and
Ep=300 keV), the derived peak flux upper limit is ~2.4e-07 (1.2e-07)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.
We report for completeness and in order of FAP, all excesses
identified in the search region. We find 4 likely background
T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP  
12.5 | 0.45 | 3.3 | 0.432 +/- 0.122 +/- 0.117 | 0.328 
-64.5 | 0.9 | 3.4 | 3.33 +/- 0.863 +/- 0.9 | 0.663 
-41.5 | 0.15 | 4.3 | 0.939 +/- 0.213 +/- 0.254 | 0.681 
-86.8 | 1.3 | 3.3 | 2.75 +/- 0.717 +/- 0.743 | 0.76  
Note that FAP estimates (especially at timescales above 2s) may be
further affected by enhanced non-stationary local background
noise. This list excludes any excesses for which FAP is close to

All results quoted are preliminary.

This circular is an official product of the INTEGRAL Multi-Messenger

[1] Savchenko et al. 2017, A&A 603, A46 [2] Savchenko et al. 2012, A&A
541A, 122S
GCN pipeline version: 88154a3

Alexis Coleiro
Ma��tre de conf��rences - Universit�� Paris Diderot
Laboratoire Astroparticule et Cosmologie (APC)
10 rue Alice Domon et L��onie Duquet
75205 Paris Cedex 13 (France)
Tel.: +33 1 57 27 60 59 /
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