{
  "body": "M. A. Williams (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.\nLeicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB),\nE. Ambrosi  (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), S. Dichiara\n(PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on\nbehalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nSVOM/ECLAIRs-detected burst GRB 241209B. We searched for X-ray sources\nin  3.1 ks of Photon Counting (PC) mode data. The total exposure at the\nposition of the afterglow (see below) is 3.1 ks, obtained between\nT0+50.8 ks and T0+57.9 ks.\n\nAn uncatalogued X-ray source is detected within the estimated 3-sigma\nSVOM/ECLAIRs error region (459 arcsec) and is believed to be the\nafterglow, given its positional coincidence with the SVOM/VT optical\ntransient (GCN 38516). Using 1725 s of PC mode data and 1 UVOT image,\nwe find an enhanced XRT position (using the XRT-UVOT alignment and\nmatching UVOT field sources to the USNO-B1 catalogue): RA, Dec =\n194.63185, +76.17637 which is equivalent to:\n\nRA (J2000): 12h 58m 31.64s\nDec(J2000): +76d 10' 34.9\"\n\nwith an uncertainty of 4.5 arcsec (radius, 90% confidence). This\nposition is 5.7 arcmin from the SVOM/ECLAIRs position.\tWe cannot\ndetermine at the present time whether the source is fading.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00021739.\nThe results of the full analysis of the XRT observations are available\nat https://www.swift.ac.uk/ToO_GRBs/00021739.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "bibcode": "2024GCN.38525....1W",
  "submittedHow": "email",
  "circularId": 38525,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "subject": "GRB 241209B: Swift-XRT afterglow detection",
  "createdOn": 1733841375524,
  "eventId": "GRB 241209B"
}