{
  "bibcode": "2016GCN.18815....1M",
  "body": "A. Melandri (INAF-OAB), A. P. Beardmore (U Leicester),\nD. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),\nP. D'Avanzo (INAF-OAB), P.A. Evans (U Leicester), C. Gronwall (PSU)\nand K. L. Page (U Leicester) report on behalf of the Swift Team:\n\nAt 11:24:10 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 160104A (trigger=669319).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 76.804, +11.354 which is \n   RA(J2000) = 05h 07m 13s\n   Dec(J2000) = +11d 21' 14\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed multiple weak peaks\nwith a duration of about 20 sec.  The peak count rate was ~1929 counts/sec \n(15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 11:25:30.0 UT, 79.3 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source with an enhanced position: RA, Dec 76.7965,\n11.3239 which is equivalent to:\n   RA(J2000)  = 05h 07m 11.17s\n   Dec(J2000) = +11d 19' 25.9\"\nwith an uncertainty of 2.2 arcseconds (radius, 90% containment). This\nlocation is 111 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 consistent with the Galactic value of 2.71\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White\nfilter  starting 85 seconds after the BAT trigger. No credible\nafterglow candidate has  been found in the initial data products. The\n2.7'x2.7' sub-image covers none of  the XRT error circle. The 8'x8'\nregion for the list of sources generated  on-board covers 100% of the\nXRT error circle. The list of sources is typically  complete to about\n18 mag. No correction has been made for the expected  extinction\ncorresponding to E(B-V) of 0.26. \n\nBurst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). \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": 18815,
  "createdOn": 1451907580000,
  "email": "burrows@astro.psu.edu",
  "subject": "GRB 160104A: Swift detection of a burst",
  "submitter": "David Burrows at PSU/Swift  <burrows@astro.psu.edu>",
  "eventId": "GRB 160104A"
}