{
  "bibcode": "2021GCN.29985....1D",
  "body": "James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea\n(PSU) report:\n\nSwift/BAT did not trigger on GRB 201228B (T0: 2020-12-28 15:21:45 UTC,\nFermi/GBM trigger num 630861710, GCN 29188).\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 ~16 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 27.88. 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 13.1.\n\nThe BAT position is\nRA, Dec = 35.594, 56.015 deg which is\n   RA(J2000)  = 02h 22m 22.56s\n   Dec(J2000) =  +56d 00��� 54.0���\nwith an estimated uncertainty of 3 arcmin.\n\n\nThis position is consistent with the Fermi GBM team localization (GCN 29188).\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": 29985,
  "createdOn": 1620680624000,
  "email": "aaron.tohu@gmail.com",
  "subject": "GRB 201228B: Swift/BAT-GUANO archival detection and arcminute localization",
  "submitter": "Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>",
  "eventId": "GRB 201228B"
}