{
  "bibcode": "2020GCN.27157....1B",
  "body": "D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne\n(U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U.\nLeicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo\n(INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the\nSwift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nFermi/LAT-detected burst GRB 200219C (Dirirsa et al. GCN Circ. 27151)\nin a series of observations tiled on the sky. The total exposure time\nis 2.4 ks, distributed over 4 tiles; the maximum exposure at a single\nsky location was 2.4 ks. The data were collected between T0+43.0 ks and\nT0+56.0 ks, and are entirely in Photon Counting (PC) mode. \n\nTwo uncatalogued X-ray sources are detected, of which one (\"Source 2\")\nis above the RASS limit, and is therefore likely the GRB afterglow.\nUsing 2417 s of PC mode data and 5 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 = 262.50899, +10.53933 which is\nequivalent to:\n\nRA (J2000): 17h 30m 02.16s\nDec(J2000): +10d 32' 21.6\"\n\nwith an uncertainty of 2.1 arcsec (radius, 90% confidence). This\nposition is 12.9 arcmin from the Fermi/LAT position.  The light curve\nis consistent with a constant source of mean count rate 1.1e-01 ct/sec.\nA power-law fit gives an index of 0.9 (+1.4, -1.5).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.1 (+/-0.4). The\nbest-fitting absorption column is  3.2 (+1.6, -1.4) x 10^21 cm^-2, in\nexcess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.1 x 10^-11 (4.9 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     3.2 (+1.6, -1.4) x 10^21 cm^-2\nGalactic foreground: 1.2 x 10^21 cm^-2\nExcess significance: 2.4 sigma\nPhoton index:\t     2.1 (+/-0.4)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00020973.\nThe results of the full analysis of the tiled XRT observations are\navailable at https://www.swift.ac.uk/xrt_products/TILED_GRB00088.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 27157,
  "createdOn": 1582229440000,
  "email": "valerio.delia@ssdc.asi.it",
  "subject": "GRB 200219C: Swift-XRT afterglow detection",
  "submitter": "Valerio D'Elia at ASDC  <valerio.delia@ssdc.asi.it>",
  "eventId": "GRB 200219C"
}