{
  "body": "K.L. Page (U. Leicester), S. Campana (INAF-OAB), A. Melandri\n(INAF-OAR), T. Sbarrato (INAF-OAB), S. Dichiara (PSU), D.N. Burrows\n(PSU), J.J. DeLaunay (PSU), A.P. Beardmore (U. Leicester) and P.A.\nEvans (U. Leicester) reports on behalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nSVOM/ECLAIRs-detected burst GRB 261007A, also known as EP261007a (GCN\nCirc. 45828). We searched for X-ray sources in\t1.9 ks of Photon\nCounting (PC) mode data. The total exposure at the position of the\nafterglow (see below) is 1.9 ks, obtained between T0+38.5 ks and\nT0+44.0 ks.\n\nAn uncatalogued X-ray source is detected and is above the RASS 3-sigma\nupper limit at this position, and is therefore likely the GRB\nafterglow. The position of this source is also consistent with the\noptical counterpart initially discovered by KAIT (GCN Circ. 45825).\nUsing 1918 s of PC mode data and 2 UVOT images, we find an enhanced XRT\nposition (using the XRT-UVOT alignment and matching UVOT field sources\nto the USNO-B1 catalogue): RA, Dec = 11.61403, -17.69197 which is\nequivalent to:\n\nRA (J2000): 00h 46m 27.37s\nDec(J2000): -17d 41' 31.1\"\n\nwith an uncertainty of 2.7 arcsec (radius, 90% confidence). This\nposition is 2.4 arcmin from the SVOM/ECLAIRs position.\tThe light curve\nis currently consistent with a constant source of mean count rate\n1.3e-01 ct/sec. \n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.74 (+0.29, -0.21). The\nbest-fitting absorption column is  3.7 (+7.0, -1.6) x 10^20 cm^-2,\nconsistent with the Galactic value of 2.1 x 10^20 cm^-2 (Willingale et\nal. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 3.7 x 10^-11 (4.0 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     3.7 (+7.0, -1.6) x 10^20 cm^-2\nGalactic foreground: 2.1 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.74 (+0.29, -0.21)\n\nThe results of the XRT-team automatic analysis are available at\nhttps://www.swift.ac.uk/xrt_products/00021917.\nThe results of the full analysis of the XRT observations are available\nat https://www.swift.ac.uk/ToO_GRBs/00021917.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "eventId": "GRB 261007A",
  "createdOn": 1791444141524,
  "circularId": 45850,
  "subject": "GRB 261007A: Swift-XRT afterglow detection",
  "submittedHow": "email"
}