[vsnet-grb-info 28244] Fermi-LAT Gamma-ray Observations of IceCube-210629A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30347
SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-210629A
DATE:    21/06/30 17:30:29 GMT
FROM:    Simone Garrappa at DESY  <simone.garrappa at desy.de>

S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and R. de 
Menezes (Univ. of Sao Paulo, Univ. of Wuerzburg) on behalf of the 
Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy 
IC210629A neutrino event (GCN 30342) 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 2021-06-29 at 18:09:44 UT 
(T0) with J2000 position RA = 340.75 (+ 1.11, - 2.23) deg, Decl. = 
+12.94 (+ 0.91, - 0.93) deg (90% PSF containment). No cataloged >100 MeV 
gamma-ray source is located within the 90% IC210629A localization region.

We searched for intermediate (days to years) timescale emission from a 
new gamma-ray transient source. Preliminary analysis indicates no 
significant (> 5 sigma) new excess emission (> 100 MeV) at the IC210629A 
best-fit position. Assuming a power-law spectrum (photon index = 2.0 
fixed) for a point source at the IC210629A best-fit position, the >100 
MeV flux upper limit (95% confidence) is < 3.8e-10 ph cm^-2 s^-1 for 
~12-years (2008-08-04 to 2021-06-29 UTC), and < 3.4e-9 (< 6.5e-8) 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 the IceCube event region will continue. For these 
observations the Fermi-LAT contact persons are S. Garrappa 
(simone.garrappa at desy.de) and S. Buson (sara.buson at uni-wuerzburg.de).

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.