{
  "bibcode": "2021GCN.29984....1D",
  "body": "James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea\n(PSU) report:\n\nSwift/BAT did not trigger on GRB 200716A (T0: 2020-07-16 01:26:37.76\nUTC),  Fermi/GBM team (GCNs 28109, 28120), BALROG (GCN 28112), AGILE\n(GCN 28116), AstroSat CZTI (GCN 28117), IPN (GCN 28121).\n\nThe Fermi/GBM notice, distributed in near real-time, triggered the\nSwift Mission Operations Center operated Gamma-ray Urgent Archiver for\nNovel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).\n\nUpon trigger by this notice, GUANO sent a command to the Swift Burst\nAlert Telescope (BAT) to save 200 seconds of BAT event-mode data from\n[-50,+150] seconds around the time of the burst. All the requested\nevent mode data was delivered to the ground.\n\nThe burst is detected in BAT with a duration of at least 60 seconds.\n\nThis burst was not localized in our low-latency analysis at the time.\nAn updated and improved version of the targeted search pipeline was\nrecently re-run on archival data and this burst was recovered.\n\nWith a maximum likelihood analysis (DeLaunay et al. 2021, in prep.) on\nthe event-mode data we detect a location for the burst with a square\nroot of the test statistic, sqrt(TS), of 110.96. The sqrt(TS) behaves\nsimilarly to SNR.\nUsing the normal BAT imaging technique, we find the same location for\nthe GRB with an SNR of 8.5.\n\nThe partial coding fraction for this burst was 1%.  The SNR in the\nimage is significantly lower than the sqrt(TS) as the maximum\nlikelihood analysis is capable of considering counts from the burst\ndeposited on the detector that arrive via lines of sight that do not\npass through the coded mask. For the case of bursts at low partial\ncoding fractions, this yields a substantial sensitivity improvement\nover imaging.\n\nThe BAT position is\nRA, Dec = 139.348, -16.712 deg which is\n   RA(J2000)  = 09h 17m 23.5s\n   Dec(J2000) =  -16d 42��� 43.2���\nwith an estimated uncertainty of 5 arcmin.\n\nThis position is consistent with the ~1/2 square degree IPN\nlocalization (GCN 28121).\n\nGUANO is a fully autonomous, extremely low latency, spacecraft\ncommanding pipeline designed for targeted recovery of BAT event mode\ndata around the times of compelling astrophysical events to enable\nmore sensitive GRB searches.\n\nA live reporting of Swift/BAT event data recovered by GUANO can be\nfound at: https://www.swift.psu.edu/guano/",
  "circularId": 29984,
  "createdOn": 1620680528000,
  "email": "aaron.tohu@gmail.com",
  "subject": "GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization",
  "submitter": "Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>",
  "eventId": "GRB 200716A"
}