{
  "bibcode": "2022GCN.32076....1D",
  "body": "S. Dichiara (PSU), J.D. Gropp (PSU), D. M. Palmer (LANL) and\nB. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 23:20:21 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 220521A (trigger=1107466).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 275.197, +10.384 which is \n   RA(J2000) = 18h 20m 47s\n   Dec(J2000) = +10d 23' 03\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a double-peaked\nstructure with a duration of about 15 sec.  The peak count rate\nwas ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 23:21:57.7 UT, 96.3 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 275.22891, 10.37262 which is equivalent\nto:\n   RA(J2000)  = 18h 20m 54.94s\n   Dec(J2000) = +10d 22' 21.4\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 120 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 consistent with the Galactic value of 1.87\nx 10^21 cm^-2 (Willingale et al. 2013). \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. Results from the 2.7'x2.7' sub-image\nare not available at this time. The 8'x8' region for the list of sources\ngenerated on-board covers 100% of the XRT error circle. The list of sources is\ntypically complete to about 18 mag. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.185. \n\nBurst Advocate for this burst is S. Dichiara (simonedichiara55 AT gmail.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/)",
  "circularId": 32076,
  "createdOn": 1653175911000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 220521A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 220521A"
}