{
  "createdOn": 1690513623681,
  "submitter": "David Palmer at LANL <palmer@lanl.gov>",
  "body": "\nC. Salvaggio (INAF-OAB), P. D'Avanzo (INAF-OAB), S. Laha (GSFC/UMBC),\nD. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII) and\nM. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 02:50:03 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 230728A (trigger=1181187).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 343.539, +28.151 which is \n   RA(J2000) = 22h 54m 09s\n   Dec(J2000) = +28d 09' 03\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  Due to a telemetry gap, BAT lightcurve information\nis not immediately available. \n\nThe XRT began observing the field at 02:51:33.5 UT, 90.3 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source with an enhanced position: RA, Dec 343.51530,\n28.17470 which is equivalent to:\n   RA(J2000)  = 22h 54m 03.67s\n   Dec(J2000) = +28d 10' 28.9\"\nwith an uncertainty of 1.9 arcseconds (radius, 90% containment). This\nlocation is 113 arcseconds from the BAT onboard position, within the\nBAT error circle. This position may be improved as more data are\nreceived; the latest position is available at\nhttps://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 (6.29 x\n10^20 cm^-2, Willingale et al. 2013), with an excess column of 7.2\n(+2.52/-2.21) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 7.13e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 99 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. The typical 3-sigma upper limit has been about 19.6 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.079. \n\nBurst Advocate for this burst is C. Salvaggio (chiara.salvaggio AT inaf.it). \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",
  "circularId": 34282,
  "eventId": "GRB 230728A",
  "subject": "GRB 230728A: Swift detection of a burst",
  "submittedHow": "email",
  "bibcode": "2023GCN.34282....1S"
}