{
  "bibcode": "2007GCN..6587....1P",
  "body": "M. Perri, G. Stratta (ASDC)  and S.T. Holland (CRESST/GSFC/USRA)\nreport on behalf of the Swift XRT team:\n\nWe have analysed the first 3 orbits of Swift XRT data from the possible\nburst GRB 070628 (Holland et al., GCN Circ. 6584). Using an exposure\ntime of 6.3 ks the refined XRT position is RA (J2000) = 115.275833,\nDec (J2000) = -20.279750, corresponding to:\nRA(J2000) = 07h 41m 06.2s\nDec(J2000) = -20d 16' 47.1\"\nwith an uncertainty of 3.5\" (90% containment). This is 0.5 arcmin from\nthe BAT position (GCN Circ. 6584) and 1.4 arcsec from the UVOT position\n(Gronwall et al. GCN Circ. 6585).\n\nThe XRT light-curve in the time interval from T+116s to T+14ks shows\na fading behavior with superimposed flaring activity. More data are being\ncollected to monitor the light-curve evolution.\n\nThe X-ray spectrum covering the time period from  T+1.1ks to T+14ks\nis well fit by an absorbed power law with a photon index of  2.2 +/- 0.1\nand a total column density of NH=(7.5+/-0.7)e21 cm**-2. We note that\nthe Galactic column density in the direction of the source is\n7.35e21 cm**-2 (Dickey & Lockman 1990).\n\nThis circular is an official product of the Swift XRT team.",
  "circularId": 6587,
  "createdOn": 1183075318000,
  "email": "perri@asdc.asi.it",
  "subject": "GRB 070628: Swift XRT refined analysis",
  "submitter": "Matteo Perri at ISAC/ASDC  <perri@asdc.asi.it>",
  "eventId": "GRB 070628"
}