{
  "bibcode": "2013GCN.14263....1M",
  "body": "Daniele Malesani (DARK/NBI), Bin-Bin Zhang (PSU), David N. Burrows \n(PSU), Dirk Grupe (PSU), report on behalf of the Swift-XRT team:\n\nThe Swift spacecraft observed the ground-discovered BAT GRB 130305A \n(Cummings & Palmer, GCN 14257), also detected by Fermi GBM and LAT (Yu & \nXiong, GCN 14261; Guiriec et al., GCN 14260), Konus/Wind (Golenetskii et \nal., GCN 14262) and INTEGRAL SPI-ACS.\n\nWe have analysed 1.8 ks of XRT data, from 31.0 ks to 47.2 ks after the \nSwift/BAT trigger. The data are entirely in photon counting (PC) mode. \nAn X-ray source is detected within the Swift/BAT error circle. The XRT \nposition is RA, Dec = 116.74762, +52.03332 which is equivalent to:\n\nRA (J2000) = 07 46 59.43\nDec(J2000) = +52 01 60.0\n\nwith an uncertainty of 3.8 arcsec (radius, 90% confidence). This \nposition is 49 arcsec from the Swift/BAT position.\n\nA spectrum formed from the PC mode data can be fitted with an absorbed \npower-law with a photon spectral index of 2.0 (+0.7, -0.6). The \nbest-fitting absorption column is  4.1 (+3.6, -2.5) x 10^21 cm^-2, in \nexcess of the Galactic value of 4.8 x 10^20 cm^-2 (Kalberla et al. \n2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion \nfactor deduced from this spectrum  is 4.3 x 10^-11 (7.3 x 10^-11) erg \ncm^-2 count^-1.\n\nA summary of the PC-mode spectrum is thus:\nTotal column:         4.1 (+3.6, -2.5) x 10^21 cm^-2\nGalactic foreground: 4.8 x 10^20 cm^-2\nExcess significance: 2.4 sigma\nPhoton index:         2.0 (+0.7, -0.6)\n\nFurther observations by Swift are ongoing. The results of the XRT-team \nautomatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00020234.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 14263,
  "createdOn": 1362585004000,
  "email": "malesani@dark-cosmology.dk",
  "subject": "GRB 130305A: Swift/XRT detection of the afterglow",
  "submitter": "Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>",
  "eventId": "GRB 130305A"
}