{
  "eventId": "GRB 251203B",
  "submittedHow": "email",
  "body": "S. Lanava (PSU), P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi \n(INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio\n(INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A.\nD'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara\n(PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester),\nK.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T.\nSbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf\nof the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source\nsb25120304, collecting 972 s of Photon Counting (PC) mode data between T0+4.6 ks and\nT0+5.7 ks after the trigger. A candidate counterpart has been found. The details of\nthis source are:\n\n  Source 1 (SWIFT J011326.9+000111):\n  ==================================\n    RA (J2000.0):   18.3625  =\t01 13 27.00\n    Dec (J2000.0):  +0.0198  =\t+00 01 11.3\n    Error:\t    3.5 (arcsec, radius, 90% confidence).\n    Detect flag:    GOOD\n    Distance:\t    5.9 arcmin from the SVOM/ECLAIRs position.\n    Mean rate:\t    1.785 +/- 0.088 ct s^-1\n    Mean flux:\t    (5.76 +/- 0.28)e-11 erg cm^-2 s^-1\n    Peak rate:\t    2.72 +/- 0.62 ct s^-1\n    Peak flux:\t    (8.8 +/- 2.0)e-11 erg cm^-2 s^-1\n    ECF:\t    3.23e-11 erg cm^-2 ct^-1\n\t\t      assuming NH=1.00e+21 cm^-2, gamma=2.03\n\t\t      determined from a spectral fit.\n    This matches a catalogued X-ray source 4XMM J011326.8+000107\n    in the XMM-NEWTON/XMMSSC catalogue. Details:\n    Separation:     3.3\" from the XRT source\n    Cat Rate:\t    2.7e-01 +/- 1.0e-02 ct s^-1 \n    Cat Flux:\t    2.4e-12 +/- 8.9e-14 erg cm^-2 s^-1 (0.3-10 keV)\n\t\t      so the source  is 4.3-sigma above the catalogued flux.\n    The source may be fading, at the 0.3-sigma level.\n    A SIMBAD object `Gaia DR3 2534635509050352256' is 4.2\" away.\n    There is 1 2MASS object within the source's 3-sigma error radius.\n\nAs pointed out by Malesani et al. (GCNs 42979), Brunet et al. (GCN 42981) and\nPerez-Garcia at al. (GCN 42982) this suggest that the transient is due to flaring\nactivity from this star.\n\n\nWe have detected a total of 4 sources.\tThese have been automatically classified as\nfollows:\n  * 0 likely counterparts\n  * 1 candidate counterpart\n  * 3 uncatalogued X-ray sources\n  * 0 known X-ray sources\n\nUncatalogued X-ray sources\n--------------------------\n\n  Source 2 (SWIFT J011329.9-000900):\n  ==================================\n    RA (J2000.0):   18.3746  =\t01 13 29.90\n    Dec (J2000.0):  -0.1502  =\t-00 09 00.7\n    Error:\t    7.9 (arcsec, radius, 90% confidence).\n    Detect flag:    POOR\n    Distance:\t    10.3 arcmin from the SVOM/ECLAIRs position.\n    Mean rate:\t    (6.9 [+4.4, -3.1])e-3 ct s^-1\n    Mean flux:\t    (3.0 [+1.9, -1.3])e-13 erg cm^-2 s^-1\n    Peak rate:\t    (6.9 [+4.4, -3.1])e-3 ct s^-1\n    Peak flux:\t    (3.0 [+1.9, -1.3])e-13 erg cm^-2 s^-1\n    XMM UL:\t    1.8e-14 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\n  Source 3 (SWIFT J011422.6+000036):\n  ==================================\n    RA (J2000.0):   18.5945  =\t01 14 22.68\n    Dec (J2000.0):  +0.0102  =\t+00 00 36.7\n    Error:\t    8.3 (arcsec, radius, 90% confidence).\n    Detect flag:    POOR\n    Distance:\t    8.1 arcmin from the SVOM/ECLAIRs position.\n    Mean rate:\t    (6.2 [+4.0, -2.8])e-3 ct s^-1\n    Mean flux:\t    (2.6 [+1.7, -1.2])e-13 erg cm^-2 s^-1\n    Peak rate:\t    (6.2 [+4.0, -2.8])e-3 ct s^-1\n    Peak flux:\t    (2.6 [+1.7, -1.2])e-13 erg cm^-2 s^-1\n    XMM UL:\t    1.1e-14 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\n  Source 4 (SWIFT J011327.9-000300):\n  ==================================\n    RA (J2000.0):   18.3663  =\t01 13 27.91\n    Dec (J2000.0):  -0.0501  =\t-00 03 00.4\n    Error:\t    9.4 (arcsec, radius, 90% confidence).\n    Detect flag:    POOR\n    Distance:\t    6.4 arcmin from the SVOM/ECLAIRs position.\n    Mean rate:\t    (-1.0 +/- -1.0)e0 ct s^-1\n    Mean flux:\t    (-4.3 +/- -4.3)e-11 erg cm^-2 s^-1\n    Peak rate:\t    (4.0 [+3.3, -2.3])e-3 ct s^-1\n    Peak flux:\t    (1.7 [+1.4, -1.0])e-13 erg cm^-2 s^-1\n    XMM UL:\t    3.6e-14 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    There is 1 2MASS object within the source's 3-sigma error radius.\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_FIELD00054.\n\nThis circular is an official product of the Swift-XRT team.\n\n\n",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "subject": "GRB 251203B: Swift-XRT observations",
  "bibcode": "2025GCN.42983....1L",
  "circularId": 42983,
  "createdOn": 1764801355156
}