{
  "bibcode": "2022GCN.31411....1G",
  "body": "J. D. Gropp (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester),\nJ.P. Osborne (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo\n(INAF-OAB), M.G. Bernardini (INAF-OAB), A. Tohuvavohu (U. Toronto) and\nP.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nFermi/LAT-detected burst GRB 220107B (Arimoto et al. GCN Circ. 31409)\nin a series of observations tiled on the sky. The total exposure time\nis 1.3 ks, distributed over 2 tiles; the maximum exposure at a single\nsky location was 1.0 ks. The data were collected between T0+35.7 ks and\nT0+36.2 ks, and are entirely in Photon Counting (PC) mode. \n\nAn uncatalogued X-ray source is detected and is above the RASS 3-sigma\nupper limit at this position, and is therefore likely the GRB\nafterglow. Using 546 s of PC mode data and 1 UVOT image, we find an\nenhanced XRT position (using the XRT-UVOT alignment and matching UVOT\nfield sources to the USNO-B1 catalogue): RA, Dec = 216.40652, +20.17064\nwhich is equivalent to:\n\nRA (J2000): 14h 25m 37.56s\nDec(J2000): +20d 10' 14.3\"\n\nwith an uncertainty of 3.4 arcsec (radius, 90% confidence). This\nposition is 11.5 arcmin from the Fermi/LAT position.  The source has a\nmean count rate of 1.3e-01 ct/sec; while we cannot determine at the\npresent time whether it is fading, the fact that the source is well\nabove RASS limit strongly suggests it is the X-ray afterglow of GRB\n220107B. More data are currently being collected.\n\nThe results of the XRT-team automatic analysis of the likely afterglow\nare at https://www.swift.ac.uk/xrt_products/TILED_GRB00103/Source1.php.\n\nThe results of the full analysis of the tiled XRT observations are\navailable at https://www.swift.ac.uk/xrt_products/TILED_GRB00103.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 31411,
  "createdOn": 1641634401000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 220107B: Swift-XRT afterglow detection",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 220107B"
}