{
  "createdOn": 1716423464104,
  "submittedHow": "web",
  "body": "S. Dalessi (UAH), S. Bala (USRA), P. Veres (UAH), and C. Meegan (UAH) report on behalf of the Fermi-GBM Team:\n\nAstroSat CZTI detected GRB 240516B at 03:41:01.51 UT (GCN 36527). There was a\nFermi-GBM onboard trigger 259s before the event (GCN 36499) and due to the Fermi-GBM trigger latency, were unable to trigger on this event.\n\nThe GBM targeted search (Goldstein et al. 2019 arXiv:1903.12597), the most sensitive, coherent search for GRB-like signals identified a transient most significantly on the 8.192 s\ntimescale, with a false alarm rate of 1.1e-05 Hz, using the standard search protocol with a S/N of 15. \n\nThe GBM targeted search event was found with the highest\nsignificance with a \"normal\" spectrum (Band function with \nEpeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.\n\n\nThe on-ground calculated location, using the Fermi GBM trigger data,\nis RA = 145.4, Dec = -9.8 (J2000 degrees, equivalent to\nJ2000 3h 5m, +47d 6'), with a statistical uncertainty of 4 degrees.\n(radius, 1-sigma containment, statistical only. There is additionally a \nsystematic error which we have characterized as a core-plus-tail model, \nwith 90% of GRBs having a 3.7 deg error and a small tail suffering a \nlarger than 10 deg systematic error (Connaughton et al. 2015, ApJS, 216, 32)).\n\nThe angle from the Fermi LAT boresight is 41 degrees.\n\nThe GBM light curve single emission episode with a duration (T90)\nof about 50 s (50-300 keV). The time-averaged spectrum\nfrom T0+259.1 to T0+309.0 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -0.44 +/- 0.12 and the cutoff energy,\nparameterized as Epeak, is 220 +/- 19 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(6.15 +/- 0.36)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+278.9 s in the 10-1000 keV band is 2.6 +/- 0.2 ph/s/cm^2.\n\nThe spectral analysis results presented above are preliminary;\nfinal results will be published in the GBM GRB Catalog:\nhttps://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html\n\nFor Fermi GBM data and info, please visit the official Fermi GBM Support Page:\nhttps://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"",
  "subject": "Fermi GBM Sub-Threshold Detection of GRB 240516B",
  "format": "text/plain",
  "circularId": 36534,
  "bibcode": "2024GCN.36534....1D",
  "submitter": "Sarah Dalessi at UAH <sd0104@uah.edu>",
  "eventId": "GRB 240516B"
}