{
  "subject": "GRB 250507A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "circularId": 40389,
  "eventId": "GRB 250507A",
  "submittedHow": "email",
  "bibcode": "2025GCN.40389....1O",
  "createdOn": 1746655338505,
  "body": "J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore\n(U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E.\nAmbrosi  (INAF-IASFPA) , M. A. Williams (PSU), S. Dichiara (PSU), J.A.\nKennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the\nSwift-XRT team:\n\nWe have analysed 1.8 ks of XRT data for GRB 250507A, from 7.4 ks to\n12.5 ks after the  SVOM/ECLAIRs trigger. The data are entirely in\nPhoton Counting (PC) mode.  We detect an uncatalogued X-ray source\nwithin the SVOM/ECLAIRs 90% C.L. error region (GCN #40374) at RA, Dec =\n183.06416, -23.5888 which is equivalent to:\n\nRA (J2000): 12h 12m 15.40s\nDec (J2000): -23d 35' 19.6\"\n\nwith an uncertainty of 4.2 arcsec (radius, 90% confidence). This\nposition is 15.6 arcsec from the SVOM/MXT position (GCN #40381) and 2.5\narcsec from the source detected by EP-FXT (GCN #40385).\n\nThe source has a mean count rate of 2.6e-02 ct/sec and a flux of       \n1.11 (+0.21, -0.20) × 10^-12 erg cm^-2 s^-1 (0.3-10 keV); we cannot\ndetermine at the present time whether it is fading. However, the\ndecrease in flux compared to the SVOM/MXT observation suggests this\nsource is the afterglow. \n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00019769.\n\nThis circular is an official product of the Swift-XRT team.\n\n"
}