{
  "bibcode": "2018GCN.22326....1M",
  "body": "A. Melandri (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A.\nKennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester),\nP. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and P.A. Evans (U. Leicester)\nreport on behalf of the Swift-XRT team:\n\nSwift-XRT has conducted further observations of the field of the\nSwift/BAT-detected burst GRB 180103A (Beardmore et al. GCN Circ.\n22305). The observations now extend from T0+344.2 ks to T0+849.2 ks.\nThe source previously reported by Melandri et al. (GCN Circ. 22308),\n\"Source 1\", is fading with 3-sigma significance, and is therefore\nlikely the GRB afterglow. Using 995 s of PC mode data and 1 UVOT image,\nwe find an enhanced XRT position (using the XRT-UVOT alignment and\nmatching UVOT field sources to the USNO-B1 catalogue): RA, Dec =\n159.60155, -53.55600 which is equivalent to:\n\nRA (J2000): 10h 38m 24.37s\nDec(J2000): -53d 33' 21.6\"\n\nwith an uncertainty of 3.8 arcsec (radius, 90% confidence). This\nposition is 35 arcsec from the Swift/BAT position. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=2.53 (+0.05, -1.07).\n\nThe results of the XRT-team automatic analysis of the likely afterglow\nare at http://www.swift.ac.uk/ToO_GRBs/00020786/Source1.php.\nThe results of the full analysis of the XRT observations are available\nat http://www.swift.ac.uk/ToO_GRBs/00020786.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 22326,
  "createdOn": 1515823709000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 180103A: Swift-XRT afterglow detection",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 180103A"
}