TITLE: GCN CIRCULAR NUMBER: 41831 SUBJECT: GRB 250912A: Swift-XRT observations DATE: 25/09/14 14:45:17 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source GRB 250912A (Ducoin et al., GCN 41820; Wang et al., GCN 41826; see also Fermi GBM team, GCN 41819), collecting 2.2 ks of Photon Counting (PC) mode data between T0+11 ks and T0+55 ks after the trigger. We have detected 1 source. This has been automatically classified as an uncatalogued X-ray source. Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J010009.7+111047): ================================== RA (J2000.0): 15.0405 = 01 00 09.72 Dec (J2000.0): +11.1797 = +11 10 46.9 Error: 7.3 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 6.8 arcmin from the SVOM/ECLAIRs position. Mean rate: (3.6 [+2.0, -1.5])e-3 ct s^-1 Mean flux: (2.7 [+1.5, -1.1])e-13 erg cm^-2 s^-1 Peak rate: (3.6 [+2.0, -1.5])e-3 ct s^-1 Peak flux: (2.7 [+1.5, -1.1])e-13 erg cm^-2 s^-1 ECF: 7.43e-11 erg cm^-2 ct^-1 assuming NH=5.11e+20 cm^-2, gamma=0.69 determined from a spectral fit. RASS UL: 7.3e-02 ct s^-1 (converted to XRT; 0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. We note that source 1 lies outside the MXT error region reported by Ducoin et al. (GCN 41820), so it is likely unrelated with the GRB. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00037. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41831. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...