TITLE:   GCN CIRCULAR
NUMBER:  29473
SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-210210A
DATE:    21/02/11 09:21:35 GMT
FROM:    Simone Garrappa at DESY  <simone.garrappa@desy.de>

S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg), C. C. Cheung 
(NRL) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy 
IC210210A neutrino event (GCN 29454) 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 2021-02-10 at 11:53:55.65 
UT (T0) with J2000 position RA = 206.06 (+1.40, -0.95) deg, Decl. = 4.78 
(+0.62, -0.56) deg (90% PSF containment). One cataloged >100 MeV 
gamma-ray source is located within the 90% IC200210A localization 
region. This is 4FGL J1342.7+0505 (4FGL, The Fermi-LAT collaboration 
2020, ApJS, 247, 33), associated with 4C +05.57 (Pilkington and Scott 
1965, MmRAS, 69, 183), a.k.a., PKS 1340+05 (Bolton et al. 1975 Aust.J. 
Phys. Astrophys. SuppL, No. 34, 1), at redshift z = 0.13663 (Hewett and 
Wild, 2010, MNRAS, 405, 2302). PKS 1340+05 has been classified 
spectroscopically as a BL Lac (BL Lac galaxy-dominated, de Menezes et al 
2019, A&A 630, A55) and broad-line radio galaxy (Grandi 1983, MNRAS, 
204, 691). Based on a preliminary analysis of the LAT data over the 
timescales of 1-day and 1-month prior to T0, this object is not 
significantly detected (> 5 sigma).

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 IC210210A 
best-fit position. Assuming a power-law spectrum (photon index = 2.0 
fixed) for a point source at the IC210210A best-fit position, the >100 
MeV flux upper limit (95% confidence) is < 6.1e-10 ph cm^-2 s^-1 for 
~12-years (2008-08-04 to 2021-02-10 UTC), and < 9.8e-9 (< 1e-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 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.