{
  "bibcode": "2016GCN.18912....1H",
  "body": "L. M. Z. Hagen (PSU), D. N. Burrows (PSU), P.A. Evans (U Leicester),\nJ. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),\nF. E. Marshall (NASA/GSFC), L. M. McCauley (PSU),\nK. L. Page (U Leicester) and B. Sbarufatti (INAF-OAB/PSU) report on\nbehalf of the Swift Team:\n\nAt 13:50:37 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 160121A (trigger=671231).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 109.079, -23.578 which is \n   RA(J2000) = 07h 16m 19s\n   Dec(J2000) = -23d 34' 40\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single FRED-\nshaped peak with a duration of about 15 sec.  The peak count rate\nwas ~1700 counts/sec (15-350 keV), at ~2 sec after the trigger. \n\nThe XRT began observing the field at 13:52:08.7 UT, 91.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 109.0890, -23.5920\nwhich is equivalent to:\n   RA(J2000)  = 07h 16m 21.35s\n   Dec(J2000) = -23d 35' 31.3\"\nwith an uncertainty of 2.4 arcseconds (radius, 90% containment). This\nlocation is 60 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 5.26\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of nominal 250.000 seconds with the U filter\nstarting 151 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. Data from the 2.7'x2.7' sub-image are\nnot available at this time. The 8'x8' region for the list of sources generated\non-board covers 100% of the XRT error circle. The list of sources is typically\ncomplete to about 18.0 mag. No correction has been made for the expected\nextinction corresponding to E(B-V) of 0.66. \n\nBurst Advocate for this burst is L. M. Z. Hagen (lea.zernow.hagen 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/too.html.)",
  "circularId": 18912,
  "createdOn": 1453384933000,
  "email": "burrows@astro.psu.edu",
  "subject": "GRB 160121A: Swift detection of a burst",
  "submitter": "David Burrows at PSU/Swift  <burrows@astro.psu.edu>",
  "eventId": "GRB 160121A"
}