{
  "bibcode": "2014GCN.15683....1G",
  "body": "Dirk Grupe (Swift MOC, PSU)  reports on behalf of the \nSwift team:\n\nWe report on further Swift XRT observations of the field of the \nFERMI/LAT-discovered GRB 131209A (Vianello et al., GCN circ. \n15587). As reported in GCN circular 15592 (Grupe & Breeveld) \nthere was one uncatalogued X-ray source found within the IPN error\nbox reported by Hurley et al. (GCN circ. 15588). We followed this\nsource  with Swift on 2013-December 17. This observation \nsuggested a decaying source with a decay slope of about 1. \nAlthough this is a rather flat decay slope during the normal decay \nphase of a GRB X-ray afterglow, it is not uncommon (e.g. Grupe et \nal. 2013, ApJS, 209, 20). Nevertheless, it is also consistent with\na variability by a factor of 2.5 which is quite common for an AGN\n(e.g. Grupe et al. 2010, ApJS, 187, 64). Therefore the data were\nnot conclusive. We therefore performed two additional observations\nwhich were performed on 2014-January 02 and 03. During the\n2014-January 02 observation the source had brightened again to a\ncount rate in the XRT of (6.4+2.2-1.7)e-3 counts s^-1 and then \ndropped again down to (1.8+1.1-0.8)e-3 counts s^-1 during the\nJanuary 03 observation. These observations suggest that the\nuncatalogued source in the IPN error box is not the X-ray\nafterglow of GRB 131209A. The rapid X-ray variability may suggest\nthat this is either a Narrow Line Seyfert 1 Galaxy or a blazar if\nthis is a background AGN. \n\n\nThis report is an official product of the Swift team.",
  "circularId": 15683,
  "createdOn": 1388891193000,
  "email": "dxg35@psu.edu",
  "subject": "GRB 131209A: Further Swift XRT  observations",
  "submitter": "Dirk Grupe at PSU/Swift-XRT  <dxg35@psu.edu>",
  "eventId": "GRB 131209A"
}