TITLE: GCN CIRCULAR NUMBER: 35531 SUBJECT: GRB 240112C: Swift-XRT refined Analysis DATE: 24/01/13 10:19:51 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.3 ks of XRT data for GRB 240112C, from 97 s to 45.8 ks after the BAT trigger. The data comprise 39 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. Using 2660 s of PC mode data and 6 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 270.64402, +24.48893 which is equivalent to: RA (J2000): 18h 02m 34.56s Dec(J2000): +24d 29' 20.2" with an uncertainty of 2.0 arcsec (radius, 90% confidence). The light curve can be modelled with an initial power-law decay with an index of alpha=0.61 (+0.04, -0.48), followed by a break at T+5970 s to an alpha of 1.30 (+0.18, -0.20). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.92 (+0.14, -0.13). The best-fitting absorption column is 2.0 (+0.5, -0.4) x 10^21 cm^-2, in excess of the Galactic value of 1.3 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 3.6 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.0 (+0.5, -0.4) x 10^21 cm^-2 Galactic foreground: 1.3 x 10^21 cm^-2 Excess significance: 2.5 sigma Photon index: 1.92 (+0.14, -0.13) If the light curve continues to decay with a power-law decay index of 1.30, the count rate at T+24 hours will be 0.015 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.3 x 10^-13 (7.0 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01208389. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/35531. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...