{
  "circularId": 38256,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "createdOn": 1731792456732,
  "submittedHow": "email",
  "bibcode": "2024GCN.38256....1B",
  "subject": "GRB 241115A: Swift-XRT afterglow detection",
  "eventId": "GRB 241115A",
  "body": "R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR),\nD.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P.\nOsborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U.\nLeicester) reports on behalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nSwift-BAT-detected burst GRB 241115A, collecting 11.3 ks of Photon\nCounting (PC) mode data between T0+92 s and T0+102.8 ks. \n\nAn uncatalogued X-ray source is detected consistent with being within\n296 arcsec of the Swift-BAT position and is above the RASS 3-sigma\nupper limit at this position and fading with >3-sigma significance, and\nis therefore likely the GRB afterglow. Using 2620 s of PC mode data and\n5 UVOT images, we find an enhanced XRT position (using the XRT-UVOT\nalignment and matching UVOT field sources to the USNO-B1 catalogue):\nRA, Dec = 86.77097, -0.67462 which is equivalent to:\n\nRA (J2000): 05h 47m 05.03s\nDec(J2000): -00d 40' 28.6\"\n\nwith an uncertainty of 2.2 arcsec (radius, 90% confidence). This\nposition is 50 arcsec from the Swift-BAT position. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.13 (+/-0.07).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.0 (+/-0.4). The\nbest-fitting absorption column is  1.7 (+0.6, -0.5) x 10^22 cm^-2, in\nexcess of the Galactic value of 3.3 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 5.9 x 10^-11 (1.2 x 10^-10) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.7 (+0.6, -0.5) x 10^22 cm^-2\nGalactic foreground: 3.3 x 10^21 cm^-2\nExcess significance: 4.5 sigma\nPhoton index:\t     2.0 (+/-0.4)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01267921.\nThe results of the full analysis of the XRT observations are available\nat https://www.swift.ac.uk/ToO_GRBs/01267921.\n\nThis circular is an official product of the Swift-XRT team.\n\n"
}