TITLE: GCN CIRCULAR NUMBER: 41010 SUBJECT: GRB 250706A: Swift-XRT refined Analysis DATE: 25/07/07 16:05:07 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> R. Brivio (INAF-OAB), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.7 ks of XRT data for GRB 250706A, from 131 s to 55.6 ks after the trigger. The data comprise 285 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 284.0176, +32.3216 which is equivalent to: RA (J2000): 18 56 04.22 Dec(J2000): +32 19 17.6 with an uncertainty of 3.5 arcsec (radius, 90% confidence). The light curve can be modelled with an initial power-law decay with an index of alpha=0.76 (+0.12, -0.13), followed by a break at T+427 s to an alpha of 2.27 (+0.18, -0.14). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.87 (+/-0.09). The best-fitting absorption column is 2.6 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 2.6 (+/-0.4) x 10^21 cm^-2 Galactic foreground: 1.2 x 10^21 cm^-2 Excess significance: 6.4 sigma Photon index: 1.87 (+/-0.09) If the light curve continues to decay with a power-law decay index of 2.27, the count rate at T+24 hours will be 3.3 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x 10^-15 (1.7 x 10^-15) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01330958. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41010. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...