{
  "bibcode": "2015GCN.18374....1K",
  "body": "H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC),\nA. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),\nC. Pagani (U Leicester), B. Sbarufatti (INAF-OAB/PSU) and\nM. H. Siegel (PSU) report on behalf of the Swift Team:\n\nAt 18:29:36 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 151001B (trigger=657321).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 336.845, +64.661, which is \n   RA(J2000)  =  22h 27m 23s\n   Dec(J2000) = +64d 39' 39\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for image triggers, there is nothing\nsignificant in the real-time TDRSS light curve. \n\nThe XRT began observing the field at 18:31:55.6 UT, 138.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source with an enhanced position: RA, Dec\n336.8384, 64.6937 which is equivalent to:\n   RA(J2000)  = 22h 27m 21.22s\n   Dec(J2000) = +64d 41' 37.4\"\nwith an uncertainty of 2.4 arcseconds (radius, 90% containment). This\nlocation is 118 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\nhttp://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 (6.51 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 6.8\n(+6.23/-4.70) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 1.89e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 148 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\n1.71. \n\nBurst Advocate for this burst is H. A. Krimm (hans.krimm 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/too.html.)",
  "circularId": 18374,
  "createdOn": 1443725073000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 151001B: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 151001B"
}