{
  "bibcode": "2011GCN.11746....1C",
  "body": "M. M. Chester (PSU), J. M. Gelbord (PSU), S. T. Holland\n(CRESST/USRA/GSFC), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA),\nN. P. M. Kuin (MSSL-UCL), F. E. Marshall (NASA/GSFC), and\nD. M. Palmer (LANL) report on behalf of the Swift team:\n\nSwift began a target of opportunity observation of OT 110215\non February 16, 2011 at 20:00:13 UT, 26.2 hours after the first\ndetection of the optical transient (Sergey and Denisenko, GCN\nCirc. 11739).  Swift data for these observations utilize Target\nID 31928.  We report a weak detection in XRT of a source\nconsistent with the position of the OT; we obtain UVOT upper\nlimits at the OT's position, but note a weak feature in the\nv-band 3.5 arc sec away.  At the time the transient was first\ndetected, the source position was far outside the Swift/BAT\nfield of view (148 degrees from the boresight) and close to the\nEarth's limb, making BAT insensitive to gamma-rays associated\nwith the event.  The transient was also out of the FoV during\nthe rebrightening reported by Sergey and Denisenko (GCN Circ.\n11739).\n\nWe have analyzed 4.6 ks of XRT data spanning from T0+26.3 to\nT0+28.5 hr.  The data are entirely in Photon Counting mode.\nWe detect a source with 3.8-sigma confidence consistent with\nthe coordinates of the OT, with a count rate of 1.8 (+/- 0.8) x\n10^-3 counts per second.  No other source is detected within 3'\nof the OT.  There is insufficient data to determine whether the\nsource is fading or to do a spectral analysis.  However, we note\nthat the six photons detected all have energies below 1.5 keV,\nsuggestive of a very soft source that would be more consistent\nwith a stellar flare than the afterglow of a GRB.\n\nThe UVOT instrument observed the field of the optical transient\nstarting 2011-02-16 at 20:02:57 UT, 26.3 hours after the start\nof the OT, and ending at 22:18:33 UT.  Only upper limits are\nobtained at the reported position of the transient.  We note a\nweak feature in the reddest filter (v) at RA = 00:26:38,\nDEC = +83:24:10.5 (J2000), 3.5 arc sec away.  The 3-sigma upper\nlimits are given below.  The magnitudes are based on the UVOT\nphotometric system (Poole et al. 2008, MNRAS, 383, 627); they\nare not corrected for the Galactic extinction corresponding to\na reddening of E_{B-V} = 0.166 mag (Schlegel et al., 1998, ApJS,\n500, 525).\n\n  Filter   exposure(sec)  magnitude\n  v         383          >20.1\n  b         383          >20.3\n  u         383          >19.8\n  uvw1      766          >20.3\n  uvm2     1092          >20.9\n  uvw2     1534          >21.3",
  "circularId": 11746,
  "createdOn": 1297984026000,
  "email": "chester@astro.psu.edu",
  "subject": "Swift XRT and UVOT Observations of OT 110215",
  "submitter": "Margaret Chester at PSU  <chester@astro.psu.edu>"
}