GRB 201203A: Swift-XRT afterglow detection
Abstract
Swift-XRT has observed GRB 201203A (Dichiara et al. GCN Circ. 28985), collecting 2.8 ks of Photon Counting (PC) mode data between T0+4.7 ks and T0+17.6 ks. One uncatalogued X-ray source is detected within the BAT error circle. Using 857 s of PC mode data and 2 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 = 38.05521, -26.51820 which is equivalent to: RA (J2000): 02h 32m 13.25s Dec(J2000): -26d 31' 05.5" with an uncertainty of 3.3 arcsec (radius, 90% confidence). This position is 107 arcsec from the BAT position. The light curve can be modelled with a power-law decay with a decay index of alpha=1.4 (+1.3, -1.1). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.9 (+0.7, -0.4). The best-fitting absorption column is consistent with the Galactic value of 1.8 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (1.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.8 (+/-7.3) x 10^20 cm^-2 Galactic foreground: 1.8 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.9 (+0.7, -0.4) If the light curve continues to decay with a power-law decay index of 1.4, the count rate at T+24 hours will be 3.4 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-14 (5.5 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/01010946. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/01010946. This circular is an official product of the Swift-XRT team.
- Publication:
-
GRB Coordinates Network
- Pub Date:
- December 2020
- Bibcode:
- 2020GCN.28990....1D