{
  "circularId": 41783,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "body": "M. Perri (SSDC & INAF-OAR), P.A. Evans (U. Leicester) and J.A. Kennea\n(PSU) report on behalf of the Swift-XRT team:\n\nThe XRT began observing the field of GRB 250911A at 02:25:07.6 UT,\n3441.5 seconds after the BAT trigger. Using promptly downlinked data we\nfind a fading, uncatalogued X-ray source located at RA, Dec 263.75102,\n-16.85448 which is equivalent to:\n   RA(J2000)  = 17h 35m 00.24s\n   Dec(J2000) = -16d 51' 16.1\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 53 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 https://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 (3.44 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.3\n(+3.44/-2.88) x 10^21 cm^-2 (90% confidence). \n\n",
  "eventId": "GRB 250911A",
  "bibcode": "2025GCN.41783....1P",
  "subject": "GRB 250911A: Swift-XRT observations",
  "submittedHow": "email",
  "createdOn": 1757567818402
}