{
  "bibcode": "2022GCN.33075....1S",
  "body": "J. Sinapius (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and S. \nGarrappa (Ruhr Universitaet Bochum) on behalf of the Fermi-LAT \ncollaboration:\n\nWe report an analysis of observations in the vicinity of the high-energy \nIC221210A neutrino event (GCN 33040) with all-sky survey data from the \nLarge Area Telescope (LAT), on board the Fermi Gamma-ray Space \nTelescope. The IceCube event was detected on 2022-12-10 at 08:35:11.23 \nUT (T0) with J2000 position RA = 332.58 (+9.84, -11.77) deg, Decl. = \n+22.75 (+8.15, -4.13) deg (90% PSF containment). Due to the large \nuncertainty on the neutrino localization, several�� cataloged gamma-ray \n(>100 MeV) sources are located within the 90% IC221210A localization \nregion (4FGL-DR3; arXiv:2201.11184; The Fermi-LAT collaboration 2020, \nApJS, 247, 33).\n\nWe searched for intermediate (days to years) timescale emission from a \nnew gamma-ray transient source. Preliminary analysis indicates no \nsignificant (> 5 sigma) new excess emission (> 100 MeV) at the IC221210A \nbest-fit position. Assuming a power-law spectrum (photon index = 2.0 \nfixed) for a point source at the IC221210A best-fit position, the >100 \nMeV flux upper limit (95% confidence) is < 1.5e-10 ph cm^-2 s^-1 for \n~13-years (2008-08-04 to 2022-12-10 UTC), and < 6.6e-9 (< 1.7e-7) ph \ncm^-2 s^-1 for a 1-month (1-day) integration time before T0.\n\nThe catalogued source 4FGL J2212.0+2356, associated with the \nflat-spectrum radio quasar PKS 2209+236, is located 1.25 deg from the \nbest-fit neutrino position. An inspection of the Fermi-LAT data over the \n14 years of LAT observations, shows that on timescales of 1-month, the \nobject is a relatively stable and faint gamma-ray emitter. Integrating \nover a time interval of 1-month prior to T0, the source is significantly \ndetected (> 5 sigma). A preliminary analysis of the data over the past \nyear, indicates that the source is undergoing enhanced activity. It is \ncurrently in a fading phase of a flaring episode that started circa \nSeptember 2022. The peak-activity flux of F = (1.4 +/- 0.2)e-7 ph cm^-2 \ns^-1, about 10 times the average 4FGL value, is observed between October \nand November 2022 (see also FAVA light curve \nhttps://fermi.gsfc.nasa.gov/ssc/data/access/lat/FAVA/LightCurve.php?ra=333.02&dec=23.93). \nThree additional sources are significantly detected (> 5 sigma) over a \ntime interval of 1-month prior to T0, with fluxes comparable to their \naverage 4FGL value.\n\nSince Fermi normally operates in an all-sky scanning mode, regular \nmonitoring of this region will continue. For these observations the \nFermi-LAT contact persons are J. Sinapius (jonas.sinapius at desy.de), \nS. Garrappa (simone.garrappa at desy.de) and S. Buson (sara.buson at \nuni-wuerzburg.de).\n\nThe Fermi-LAT is a pair conversion telescope designed to cover the \nenergy band from 20 MeV to greater than 300 GeV. It is the product of an \ninternational collaboration between NASA and DOE in the U.S. and many \nscientific institutions across France, Italy, Japan and Sweden.",
  "circularId": 33075,
  "createdOn": 1671232194000,
  "email": "simone.garrappa@desy.de",
  "subject": "Fermi-LAT gamma-ray observations of IceCube-221210A",
  "submitter": "Simone Garrappa at DESY  <simone.garrappa@desy.de>",
  "eventId": "IceCube-221210A"
}