{
  "bibcode": "2022GCN.31697....1C",
  "body": "R. Caputo (GSFC), A. P. Beardmore (U Leicester), C. Gronwall (PSU),\nJ.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (U Tampa),\nF. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),\nD. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII),\nM. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of\nthe Neil Gehrels Swift Observatory Team:\n\nAt 18:15:37 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 220306B (trigger=1095288).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 5.378, +71.354 which is \n   RA(J2000) = 00h 21m 31s\n   Dec(J2000) = +71d 21' 14\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex\nstructure with a duration of about 15 sec.  The peak count rate\nwas ~2600 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 18:17:03.3 UT, 85.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 5.38628, 71.36313 which is equivalent\nto:\n   RA(J2000)  = 00h 21m 32.71s\n   Dec(J2000) = +71d 21' 47.3\"\nwith an uncertainty of 4.0 arcseconds (radius, 90% containment). This\nlocation is 34 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 4.07\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 89 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\n0.578. \n\nBurst Advocate for this burst is R. Caputo (regina.caputo 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": 31697,
  "createdOn": 1646591202000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 220306B: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 220306B"
}