{
  "bibcode": "2021GCN.29397....1D",
  "body": "S. Dichiara (NASA/GSFC/UMCP), E. Ambrosi (INAF-IASFPA),\nS. D. Barthelmy (GSFC), V. D'Elia (SSDC), P. A. Evans (U Leicester),\nJ.D. Gropp (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL),\nA. Y. Lien (GSFC/UMBC) and K. L. Page (U Leicester) report on behalf\nof the Neil Gehrels Swift Observatory Team:\n\nAt 11:11:17 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 210205A (trigger=1030629).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 347.257, +56.312 which is \n   RA(J2000)  =  23h 09m 02s\n   Dec(J2000) = +56d 18' 45\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a multi-peak\nstructure with a duration of about 35 sec.  The peak count rate\nwas ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. \n\nThe XRT began observing the field at 11:13:32.2 UT, 134.7 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 347.2214, 56.2943 which\nis equivalent to:\n   RA(J2000)  = 23h 08m 53.13s\n   Dec(J2000) = +56d 17' 39.4\"\nwith an uncertainty of 2.6 arcseconds (radius, 90% containment). This\nlocation is 95 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 consistent with the Galactic value of 5.15\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 138 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 47% 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 large, but uncertain, extinction expected. \n\nBurst Advocate for this burst is S. Dichiara (dichiara AT umd.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/)",
  "circularId": 29397,
  "createdOn": 1612524437000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 210205A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 210205A"
}