TITLE: GCN CIRCULAR NUMBER: 11746 SUBJECT: Swift XRT and UVOT Observations of OT 110215 DATE: 11/02/17 23:07:06 GMT FROM: Margaret Chester at PSU M. M. Chester (PSU), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA), N. P. M. Kuin (MSSL-UCL), F. E. Marshall (NASA/GSFC), and D. M. Palmer (LANL) report on behalf of the Swift team: Swift began a target of opportunity observation of OT 110215 on February 16, 2011 at 20:00:13 UT, 26.2 hours after the first detection of the optical transient (Sergey and Denisenko, GCN Circ. 11739). Swift data for these observations utilize Target ID 31928. We report a weak detection in XRT of a source consistent with the position of the OT; we obtain UVOT upper limits at the OT's position, but note a weak feature in the v-band 3.5 arc sec away. At the time the transient was first detected, the source position was far outside the Swift/BAT field of view (148 degrees from the boresight) and close to the Earth's limb, making BAT insensitive to gamma-rays associated with the event. The transient was also out of the FoV during the rebrightening reported by Sergey and Denisenko (GCN Circ. 11739). We have analyzed 4.6 ks of XRT data spanning from T0+26.3 to T0+28.5 hr. The data are entirely in Photon Counting mode. We detect a source with 3.8-sigma confidence consistent with the coordinates of the OT, with a count rate of 1.8 (+/- 0.8) x 10^-3 counts per second. No other source is detected within 3' of the OT. There is insufficient data to determine whether the source is fading or to do a spectral analysis. However, we note that the six photons detected all have energies below 1.5 keV, suggestive of a very soft source that would be more consistent with a stellar flare than the afterglow of a GRB. The UVOT instrument observed the field of the optical transient starting 2011-02-16 at 20:02:57 UT, 26.3 hours after the start of the OT, and ending at 22:18:33 UT. Only upper limits are obtained at the reported position of the transient. We note a weak feature in the reddest filter (v) at RA = 00:26:38, DEC = +83:24:10.5 (J2000), 3.5 arc sec away. The 3-sigma upper limits are given below. The magnitudes are based on the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627); they are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.166 mag (Schlegel et al., 1998, ApJS, 500, 525). Filter exposure(sec) magnitude v 383 >20.1 b 383 >20.3 u 383 >19.8 uvw1 766 >20.3 uvm2 1092 >20.9 uvw2 1534 >21.3