{
  "bibcode": "2020GCN.28990....1D",
  "body": "V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (PSU), D.N.\nBurrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L.\nPage (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri\n(INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the\nSwift-XRT team:\n\nSwift-XRT has observed GRB 201203A (Dichiara et al. GCN Circ. 28985),\ncollecting 2.8 ks of Photon Counting (PC) mode data between T0+4.7 ks\nand T0+17.6 ks. \n\nOne uncatalogued X-ray source is detected within the BAT error circle.\nUsing 857 s of PC mode data and 2 UVOT images, we find an enhanced XRT\nposition (using the XRT-UVOT alignment and matching UVOT field sources\nto the USNO-B1 catalogue): RA, Dec = 38.05521, -26.51820 which is\nequivalent to:\n\nRA (J2000): 02h 32m 13.25s\nDec(J2000): -26d 31' 05.5\"\n\nwith an uncertainty of 3.3 arcsec (radius, 90% confidence). This\nposition is 107 arcsec from the BAT position. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.4 (+1.3, -1.1).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.9 (+0.7, -0.4). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 1.8 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 3.3 x 10^-11 (1.6 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.8 (+/-7.3) x 10^20 cm^-2\nGalactic foreground: 1.8 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.9 (+0.7, -0.4)\n\nIf the light curve continues to decay with a power-law decay index of\n1.4, the count rate at T+24 hours will be 3.4 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x\n10^-14 (5.5 x 10^-15) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01010946.\nThe results of the full analysis of the XRT observations are available\nat https://www.swift.ac.uk/ToO_GRBs/01010946.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 28990,
  "createdOn": 1607008311000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 201203A: Swift-XRT afterglow detection",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 201203A"
}