{
  "subject": "GRB 251111A: Swift-XRT observations",
  "submittedHow": "email",
  "body": "P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi  (INAF-IASFPA) , A.P.\nBeardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N.\nBurrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA),\nP. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro\n(INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U.\nLeicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato\n(INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the\nSwift-XRT team:\n\nSwift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source\nGRB 251111A, collecting 288 s of Photon Counting (PC) mode data between T0+7.4 ks\nand T0+7.8 ks after the trigger. We have detected 1 source.  This has been\nautomatically classified as an uncatalogued X-ray source.\n\nUncatalogued X-ray sources\n--------------------------\n\n  Source 1 (SWIFT J020926.8+051342):\n  ==================================\n    RA (J2000.0):   32.3618  =\t02 09 26.83\n    Dec (J2000.0):  +5.2284  =\t+05 13 42.2\n    Error:\t    5.7 (arcsec, radius, 90% confidence).\n    Detect flag:    GOOD\n    Distance:\t    2.0 arcmin from the SVOM/ECLAIRs position.\n    Mean rate:\t    0.0264 [+0.0127, -0.0096] ct s^-1\n    Mean flux:\t    (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1\n    Peak rate:\t    0.0264 [+0.0127, -0.0096] ct s^-1\n    Peak flux:\t    (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1\n    ECF:\t    2.73e-11 erg cm^-2 ct^-1\n\t\t      assuming NH=5.07e+20 cm^-2, gamma=2.63\n\t\t      determined from a spectral fit.\n    XMM UL:\t    2.6e-12 erg cm^-2 s^-1, (0.3-10 keV)\n\t\t      so the source is not above this 3-sigma upper limit.\n    There is no evidence for fading.\n\nThe XRT position is consistent the optical counterpart reported by the SVOM/COLIBRÍ\n(FM-GFT; López-Cámara et al., GCN Circ. 42638), LCO 1m (Wu et al., GCN Circ.\n42639) and SVOM/VT (Wu et al., GCN 42641) telescopes, as well as the Einstein Probe\nFXT X-ray detection (Cheng et al. 42643).\n\nAll fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with\ncatalogues and upper limits  from other missions, we assumed a power-law spectrum\nwith NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated.\n\nThe results of the XRT-team automatic analysis of the XRT observations, including a\nposition-specific upper limit calculator, are available at\nhttps://www.swift.ac.uk/SVOM/SVOM_FIELD00049.\n\nThis circular is an official product of the Swift-XRT team.\n\n\n",
  "circularId": 42645,
  "bibcode": "2025GCN.42645....1E",
  "eventId": "GRB 251111A",
  "createdOn": 1762869721335,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>"
}