{
  "submitter": "David Palmer at LANL <palmer@lanl.gov>",
  "circularId": 34894,
  "subject": "GRB 231028A: Swift detection of a burst",
  "body": "\nM. A. Williams (PSU), S. Dichiara (PSU), D. M. Palmer (LANL),\nT. Sakamoto (AGU) and B. Sbarufatti (INAF-OAB) report on behalf of the\nNeil Gehrels Swift Observatory Team:\n\nAt 04:09:09 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 231028A (trigger=1193078).  Swift did not slew to the \nGRB location due to an observing constraint. \nThe BAT on-board calculated location is \nRA, Dec 214.029, +20.895 which is \n   RA(J2000) = 14h 16m 07s\n   Dec(J2000) = +20d 53' 42\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex peak\nstructure with a duration of at least 18 sec, although the immediately\navailable data is truncated at T+8s due to packet loss. The peak count\nrate was ~8500 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nDue to a Sun observing constraint, Swift cannot slew to the BAT\nposition until 15:45 UT on 2023 November 22. There will thus be no XRT\nor UVOT data for this trigger before this time. \n\nSwift Triggers have recently been re-enabled while we are dealing\nwith attitude problems that can lead to star tracker Loss-of-Lock (LoL). \nWe are confident that this GRB was not caused by an LoL event because:\n1) The Swift_BAT_Position notice did not indicate a LoL. \n  (See the comments section.)\n2) This burst location was not near to a known bright source. \n3) There was a simultaneous trigger by Fermi-GBM. \n4) This is a rate-triggered burst on a 1.024 s timescale, while most LoL\nfalse triggers have been 'Image Triggers' with duration 64 s and longer. \n\nObservers should continue to be cautious (especially checking the\ncomments for LoL) in future GCN notices going forward. \n\nBurst Advocate for this burst is M. A. Williams (mjw6837 AT psu.edu). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/)\n\n",
  "createdOn": 1698467297119,
  "bibcode": "2023GCN.34894....1W",
  "submittedHow": "email",
  "eventId": "GRB 231028A"
}