{
  "bibcode": "2018GCN.22433....1C",
  "body": "J. K. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC),\nA. P. Beardmore (U Leicester), D. N. Burrows (PSU),\nP. A. Evans (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU),\nA. Y. Lien (GSFC/UMBC), Z. Liu (NAOC/U. Leicester),\nF. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),\nM. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the\nNeil Gehrels Swift Observatory Team:\n\nAt 13:10:03 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 180222A (trigger=811235).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 256.571, -36.803, which is \n   RA(J2000)  =  17h 06m 17s\n   Dec(J2000) = -36d 48' 08\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single FRED-like peak\nwith a duration of about 25 sec.  The peak count rate\nwas ~1400 counts/sec (15-350 keV), at ~2 sec after the trigger. \n\nThe XRT began observing the field at 13:11:22.7 UT, 79.2 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source located at RA, Dec 256.54119, -36.80929 which\nis equivalent to:\n   RA(J2000)  = 17h 06m 09.89s\n   Dec(J2000) = -36d 48' 33.4\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 88 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 http://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 (6.65 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 7.9\n(+11.04/-4.96) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 82 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 97% of\nthe XRT error circle. Because of the density of catalogued stars, further\nanalysis is required to report an upper limit for any afterglow in the\nsub-image. The 8'x8' region for the list of sources generated on-board covers\n100% of the XRT error circle. Because of the density of catalogued stars,\nfurther analysis is required to report an upper limit for any afterglow in the\nregion. No correction has been made for the large, but uncertain, extinction\nexpected. \n\nBurst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.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/too.html.)",
  "circularId": 22433,
  "createdOn": 1519306632000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 180222A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 180222A"
}