TITLE:   GCN CIRCULAR
NUMBER:  23927
SUBJECT: INTEGRAL observation of IceCube-190221A
DATE:    19/02/25 21:07:09 GMT
FROM:    Volodymyr Savchenko at ISDC,U of Geneve  <savchenk@in2p3.fr>

J. Rodi, A. Bazzano, L. Natalucci, F. Panessa, P. Ubertini
(IAPS-Roma, Italy)
V. Savchenko, C. Ferrigno, E. Bozzo, T. Courvoisier
(ISDC/UniGE, Switzerland)
E. Kuulkers (ESTEC/ESA, The Netherlands)
C. Sanchez (ESAC/ESA, Spain)
S. Mereghetti (INAF IASF-Milano, Italy)
J. Chenevez, S. Brandt (DTU, Denmark)
R. Diehl, A. von Kienlin (MPE, Germany)
D. Gotz, Ph. Laurent, A. Goldwurm
(DRF/Irfu/DAp Saclay/CEA, France)
A. Coleiro (APC, France)
L. Hanlon, A. Martin-Carrillo (UCD, Ireland)
J.-P. Roques, E. Jourdain, P. von Ballmoos (IRAP, France)
A. Domingo, J. M. Mas-Hesse (CAB/CSIC-INTA, Spain)
A. Lutovinov, R. Sunyaev (IKI, Russia)


Using INTEGRAL we have performed a search for a prompt gamma-ray
counterpart of the cosmic neutrino candidate IceCube-190221A
(GCN 23918).

At the time of the event (2019-02-21 08:25:40 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the neutrino
localization probability was at an angle of 20 deg with respect to
the spacecraft pointing axis. This orientation implies strongly
suppressed response of IBIS/Veto and SPI-ACS, but near-optimal
response of IBIS out of its coded Field of View.

The background within +/-300 seconds around the event was very
stable.  We do not detect any significant counterparts and estimate
a 3-sigma upper limit on the 75-2000 keV fluence of 5.2e-07 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=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
~4.7e-07 (1.7e-07) erg/cm^2/s at 1 s (8 s) time scale in 75-2000
keV energy range.