{
  "bibcode": "2019GCN.24553....1M",
  "body": "M. J. Moss (George Washington University), C. Gronwall (PSU),\nJ.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU),\nA. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),\nK. L. Page (U Leicester), M. H. Siegel (PSU) and A. Tohuvavohu (PSU)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 16:04:21 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 190515B (trigger=903845).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 98.840, +52.295 which is \n   RA(J2000) = 06h 35m 22s\n   Dec(J2000) = +52d 17' 41\"\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 20 sec.  The peak count rate\nwas ~800 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 16:05:43.7 UT, 82.4 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 98.84892, 52.31725 which\nis equivalent to:\n   RA(J2000)  = 06h 35m 23.74s\n   Dec(J2000) = +52d 19' 02.1\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 82 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.  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 1.27\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nThe initial flux in the 2.5 s image was 7.78e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 92 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 84% 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\n0.09. \n\nBurst Advocate for this burst is M. J. Moss (mikejmoss3 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/)\n\n[GCNOPS NOTE(15may19): Per author's request, the GRB name \"190515A\" was changed\nto \"190515B\" in the Subject lines in the first paragraph.]",
  "circularId": 24553,
  "createdOn": 1557937038000,
  "email": "mikejmoss3@gmail.com",
  "subject": "GRB 190515B: Swift detection of a burst",
  "submitter": "Michael Moss at George Washington U  <mikejmoss3@gmail.com>",
  "eventId": "GRB 190515B"
}