GCN Circular 25932
Subject
Fermi-LAT Gamma-ray Observations of IceCube-191001A
Date
2019-10-03T08:28:18Z (5 years ago)
From
Simone Garrappa at DESY <simone.garrappa@desy.de>
S. Garrappa (DESY-Zeuthen) and S. Buson (Univ. of Wuerzburg) on behalf
of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the high-energy
IC191001A neutrino event (GCN�25913) �with all-sky survey data from the
Large Area Telescope (LAT), on board the Fermi Gamma-ray Space
Telescope. The IceCube event was detected on 2019-10-01��20:09:18.17�UTC
(T0) with J2000 position RA =�314.08 (+6.56, -2.26) deg, Decl. =�12.94
(+1.50, -1.47) deg 90% PSF containment. Two cataloged gamma-ray sources
(The Fermi-LAT collaboration, 2019, arXiv:1902.10045)�are found within
the 90% localization error of IC191001A. These are�the millisecond
pulsar 4FGL�J2052.7+1218 (a.k.a.�PSR J2052+1218)�and the blazar
candidate of uncertain type 4FGL J2115.2+1218 (a.k.a. NVSS
J211522+121802), at a distance of 1.1 deg and�4.7 deg�from the best
fit,�respectively.
We searched for the existence of intermediate (days to years) timescale
emission from a new gamma-ray transient source.�Preliminary analysis
indicates no significant (>5sigma) new excess emission (> 100 MeV)
within the�IC191001A�90%�confidence localization. Assuming a power-law
spectrum (photon index = 2.0 fixed) for a point source at the IceCube
best-fit�position, the >100 MeV flux upper limit (95% confidence) is <
3.7e-10 ph cm^-2 s^-1 for ~11-years (2008-08-04 / 2019-10-02 UTC), <
2e-8 (< 2.9e-7) ph cm^-2 s^-1 for a 1-month (1-day) integration time
before T0.
Since Fermi normally operates in an all-sky scanning mode, regular
monitoring of this source will continue. For this source the�Fermi-LAT
contact persons are S. Garrappa (simone.garrappa atdesy.de
<http://desy.de/>) and S. Buson (sara.buson atgmail.com
<http://gmail.com/>).
The Fermi LAT is a pair conversion telescope designed to cover the
energy�band from 20 MeV to greater than 300 GeV. It is the product of an
international collaboration between NASA and DOE in the�U.S. and many
scientific institutions across France, Italy, Japan and Sweden.