{
  "createdOn": 1694423470716,
  "submitter": "K.L. Page at U Leicester <klp5@leicester.ac.uk>",
  "eventId": "GRB 230911C",
  "body": "\nE. Sonbas (Adiyaman Univ.), R. Brivio (INAF-OAB), S. Dichiara (PSU),\nM. Ferro (INAF-OAB), J.D. Gropp (PSU), A. Y. Lien (U Tampa),\nA. Melandri (INAF-OAR), K. L. Page (U Leicester), D. M. Palmer (LANL),\nT. Sakamoto (AGU), C. Salvaggio (INAF-OAB) and T. Sbarrato (INAF-OAB)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 08:47:25 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 230911C (trigger=1191188).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 226.782, -41.334 which is \n   RA(J2000) = 15h 07m 08s\n   Dec(J2000) = -41d 20' 01\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex\nstructure with a duration of about 10 sec.  The peak count rate\nwas ~700 counts/sec (15-350 keV), at ~3 sec after the trigger. \n\nThe XRT began observing the field at 08:49:24.4 UT, 119.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 226.79804, -41.32973 which is\nequivalent to:\n   RA(J2000)  = 15h 07m 11.53s\n   Dec(J2000) = -41d 19' 47.0\"\nwith an uncertainty of 4.2 arcseconds (radius, 90% containment). This\nlocation is 46 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position may be improved as more data are received;\nthe latest position is available at https://www.swift.ac.uk/sper.  We\ncannot determine whether the source is fading at the present time. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (9.36 x\n10^20 cm^-2, Willingale et al. 2013), with an excess column of 4\n(+3.90/-3.22) x 10^21 cm^-2 (90% confidence). \n\nProcessed UVOT data were not available at low latency, with the images\naffected by the attitude issues reported in GCN Circ. 34633. \n\nBurst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). \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",
  "subject": "GRB 230911C: Swift detection of a burst",
  "bibcode": "2023GCN.34655....1S",
  "circularId": 34655,
  "submittedHow": "email"
}