{
  "bibcode": "2022GCN.31466....1M",
  "body": "A. Melandri (INAF-OAB), M. G. Bernardini (INAF-OAB),\nP. D'Avanzo (INAF-OAB), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nT. M. Parsotan (GSFC/UMBC/CRESSTII), T. Sbarrato (INAF-OAB) and\nM. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 16:18:51 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 220117A (trigger=1093592).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 91.578, -28.410 which is \n   RA(J2000) = 06h 06m 19s\n   Dec(J2000) = -28d 24' 35\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a multi-peaked\nstructure with a duration of about 65 sec.  The peak count rate\nwas ~900 counts/sec (15-350 keV), at ~15 sec after the trigger. \n\nThe XRT began observing the field at 16:21:23.4 UT, 151.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 91.57277, -28.43760 which\nis equivalent to:\n   RA(J2000)  = 06h 06m 17.46s\n   Dec(J2000) = -28d 26' 15.4\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 100 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\nhttps://www.swift.ac.uk/sper.  We cannot determine whether the source\nis 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 2.57\nx 10^20 cm^-2 (Willingale et al. 2013). \n\nThe initial flux in the 2.5 s image was 6.01e-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 161 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\n0.029. \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/)",
  "circularId": 31466,
  "createdOn": 1642437076000,
  "email": "kimlpage1978@gmail.com",
  "subject": "GRB 220117A: Swift detection of a burst",
  "submitter": "Kim Page at U.of Leicester  <kimlpage1978@gmail.com>",
  "eventId": "GRB 220117A"
}