GRB 190613B: Swift-XRT refined Analysis
Abstract
We have analysed 6.3 ks of XRT data for GRB 190613B (D'Ai et al. GCN Circ. 24807), from 103 s to 19.3 ks after the BAT trigger. The data comprise 352 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 24812). The late-time light curve (from T0+5.3 ks) can be modelled with a power-law decay with a decay index of alpha=0.52 (+/-0.11). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.93 (+/-0.05). The best-fitting absorption column is 3.28 (+0.24, -0.23) x 10^21 cm^-2, in excess of the Galactic value of 6.0 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.90 (+/-0.11) and a best-fitting absorption column of 2.6 (+0.5, -0.4) x 10^21 cm^-2. 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 PC-mode spectrum is thus: Total column: 2.6 (+0.5, -0.4) x 10^21 cm^-2 Galactic foreground: 6.0 x 10^20 cm^-2 Excess significance: 7.6 sigma Photon index: 1.90 (+/-0.11) If the light curve continues to decay with a power-law decay index of 0.52, the count rate at T+24 hours will be 0.091 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.5 x 10^-12 (4.8 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00908329. This circular is an official product of the Swift-XRT team.
- Publication:
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GRB Coordinates Network
- Pub Date:
- June 2019
- Bibcode:
- 2019GCN.24823....1P