{
  "circularId": 33167,
  "createdOn": 1673658902000,
  "email": "simone.garrappa@desy.de",
  "subject": "Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A",
  "version": 2,
  "bibcode": "2023GCN.33167....1S",
  "editedOn": 1777053064372,
  "body": "J. Sinapius (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg), S. Garrappa \n(Ruhr-Universitaet Bochum) on behalf of the Fermi-LAT collaboration:\n\nWe report an analysis of observations of the vicinity of the \nIceCube-Cascade-230109A high-energy neutrino event \n(https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/137527_43987982.amon) \nwith all-sky survey data from the Large Area Telescope (LAT), on board \nthe Fermi Gamma-ray Space Telescope. The IceCube event was detected on \n2023-01-09 at 11:12:11.29 UT (T0) with J2000 position RA = (174.81 +/- \n7.07) deg, Decl. = (45.33 +/- 7.07) deg (90% PSF containment). Several \ncataloged gamma-ray (>100 MeV) sources are located within the 90% \nIceCube-Cascade-230109A localization region (4FGL-DR3; The Fermi-LAT \ncollaboration 2022, ApJS, 260, 53). Based on a preliminary analysis of \nthe LAT data over the timescales of 1-day and 1-month prior to T0, one \nof these objects is significantly detected (> 5 sigma). This source is \nthe FSRQ 4FGL J1146.9+3958 at 5.45 deg from the IC-Cascade-230109A \nbest-fit position.�� In a preliminary analysis of LAT data over 30 days \nbefore T0, the object is observed at a flux level of (9.38 +/- 1.70) e-8 \nph cm^-2 s^-1, consistent with the average value reported in 4FGL-DR3.\n\nWe searched for intermediate (days to months) timescale emission from a \nnew gamma-ray transient source. Preliminary analysis indicates no \nsignificant (> 5 sigma) new excess emission (> 100 MeV) at the \nIceCube-Cascade-230109A best-fit position. Assuming a power-law spectrum \n(photon index = 2.0 fixed) for a point source at the \nIceCube-Cascade-230109A best-fit position, the >100 MeV flux upper limit \n(95% confidence) is < 2.6e-9 (< 5.2e-8) ph cm^-2 s^-1 for a 1-month \n(1-day) integration time before T0.\n\nSince Fermi normally operates in an all-sky scanning mode, regular \nmonitoring of this source will continue. For these observations the \nFermi-LAT contact persons are J. Sinapius (jonas.sinapius at desy.de), \nS. Garrappa (simone.garrappa at ruhr-uni-bochum.de) and S. Buson \n(sara.buson at uni-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.",
  "submitter": "Simone Garrappa at DESY  <simone.garrappa@desy.de>",
  "eventId": "IceCube-Cascade 230109A",
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov>"
}