{
  "circularId": 34434,
  "subject": "GRB 230815A: Swift detection of a burst",
  "eventId": "GRB 230815A",
  "body": "\nN. J. Klingler (GSFC/UMBC/CRESSTII), C. Gronwall (PSU),\nK. L. Page (U Leicester), D. M. Palmer (LANL) and\nT. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil\nGehrels Swift Observatory Team:\n\nAt 10:49:55 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 230815A (trigger=1185505).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 184.772, -58.065 which is \n   RA(J2000) = 12h 19m 05s\n   Dec(J2000) = -58d 03' 53\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a duration of about 2 sec.  The peak count rate\nwas ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 10:52:04.0 UT, 128.1 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 184.72347, -58.05386 which\nis equivalent to:\n   RA(J2000)  = 12h 18m 53.63s\n   Dec(J2000) = -58d 03' 13.9\"\nwith an uncertainty of 3.5 arcseconds (radius, 90% containment). This\nposition may be improved as more data are received; the latest position\nis available at https://www.swift.ac.uk/sper. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (4.94 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 7.8\n(+3.75/-3.24) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 2.07e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 155 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 100% of\nthe XRT error circle. Because of the density of catalogued stars, further\nanalysis is required to report an upper limit for any afterglow in the\nsub-image. Data from the list of sources generated on-board are not available\nat this time. No correction has been made for the large, but uncertain,\nextinction expected. \n\nBurst Advocate for this burst is N. J. Klingler (noelklin AT umbc.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",
  "submittedHow": "email",
  "submitter": "K.L. Page at U Leicester <klp5@leicester.ac.uk>",
  "bibcode": "2023GCN.34434....1K",
  "createdOn": 1692098759842
}