//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32579 SUBJECT: GRB 220924A: Fermi GBM Final Real-time Localization DATE: 22/09/24 21:55:30 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 21:44:54 UT on 24 Sep 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220924A (trigger 685748699.41428 / 220924906). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 321.5, Dec = 33.8 (J2000 degrees, equivalent to J2000 21h 26m, 33d 47'), with a statistical uncertainty of 5.2 degrees. The angle from the Fermi LAT boresight is 91.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220924906/quicklook/glg_skymap_all_bn220924906.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220924906/quicklook/glg_healpix_all_bn220924906.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220924906/quicklook/glg_lc_medres34_bn220924906.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32583 SUBJECT: GRB 220924A: Swift/BAT-GUANO detection outside the coded FOV DATE: 22/09/25 22:33:21 GMT FROM: Aaron Tohuvavohu at U Toronto Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), James DeLaunay (UAlabama), Jamie A. Kennea (PSU), report: Swift/BAT did not localize GRB 220924A onboard (T0: 2022-09-24T21:44:54 UTC, Fermi/GBM GCN 32579). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, arXiv:2111.01769), detects the burst with a sqrt(TS) of 10.4 in a 16.384 s analysis time bin. NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of 2. See Section 9.1 and Figure 20 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32593 SUBJECT: GRB 220924A: Fermi GBM detection DATE: 22/09/27 01:12:16 GMT FROM: Suraj Poolakkil at UAH S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 21:44:54.41 UT on 24 September 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220924A (trigger 685748699 / 220924906, GCN 32579) which was also detected by the Swift/BAT- GUANO (Tohuvavohu et al. 2022, GCN 32583). The angle from the Fermi LAT boresight at the GBM trigger time is 91 degrees. The GBM light curve consists of multiple peaks followed by some extended emission with a duration (T90) of about 128 s (50-300 keV). The time-averaged spectrum from T0-3.07 s to T0+131.07 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.87 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 223 +/- 24 keV. The event fluence (10-1000 keV) in this time interval is (1.18 +/- 0.7)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.86 s in the 10-1000 keV band is 2.5 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"