{
  "bibcode": "2021GCN.29472....1T",
  "body": "E. Troja (NASA/GSFC/UMCP), P. A. Evans (U Leicester),\nH. A. Krimm (NSF), K. L. Page (U Leicester), B. Sbarufatti (PSU) and\nM. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 08:43:18 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 210211A (trigger=1032024).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 269.433, -46.299 which is \n   RA(J2000) = 17h 57m 44s\n   Dec(J2000) = -46d 17' 57\"\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 10 sec.  The peak count rate\nwas ~2500 counts/sec (15-350 keV), at ~4 sec after the trigger. \n\nThe XRT began observing the field at 08:44:32.2 UT, 73.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 269.4374, -46.2660\nwhich is equivalent to:\n   RA(J2000)  = 17h 57m 44.99s\n   Dec(J2000) = -46d 15' 57.7\"\nwith an uncertainty of 3.4 arcseconds (radius, 90% containment). This\nlocation is 119 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.  We cannot determine whether the source\nis 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 (1.24 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.7\n(+9.04/-6.57) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 77 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 none of\nthe XRT error circle. The 8'x8' region for the list of sources generated\non-board covers 100% of the XRT error circle. Because of the density of\ncatalogued stars, further analysis is required to report an upper limit for any\nafterglow in the region. No correction has been made for the expected\nextinction corresponding to E(B-V) of 0.126. \n\nBurst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). \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": 29472,
  "createdOn": 1613034056000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 210211A: Swift detection of a burst",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 210211A"
}