{
  "bibcode": "2021GCN.30656....1B",
  "body": "A. P. Beardmore (U Leicester), J.D. Gropp (PSU),\nF. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),\nM. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of\nthe Neil Gehrels Swift Observatory Team:\n\nAt 16:17:00 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated Cyg X-1 (trigger=1069242).  Swift slewed immediately to the source. \nThe BAT on-board calculated location is \nRA, Dec 299.819, +35.277 which is \n   RA(J2000) = 19h 59m 16s\n   Dec(J2000) = +35d 16' 37\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty). This onboard position is 12 arcminutes from the \nknown position of Cyg X-1, likely due to higher than typical attitude \nuncertainty from the star trackers. \nAs is typical for an image trigger the prompt  BAT lightcurve shows no\nevidence of structure, and the significance of the source in the BAT image\nis consistent with the typical brightness of Cyg X-1. \n\nThe XRT began observing the field at 16:19:20.2 UT, 139.8 seconds after\nthe BAT trigger. XRT found a bright X-ray source  in the field-of-view 26\narcseconds from the position of Cyg X-1, but  given the star trackers \nhad lost lock is likely consistent with this source. \n\nThere are no UVOT data available at this time.",
  "circularId": 30656,
  "createdOn": 1629305758000,
  "email": "klp5@leicester.ac.uk",
  "subject": "Swift Trigger 1069242 is Cyg X-1",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>"
}