TITLE: GCN CIRCULAR NUMBER: 21235 SUBJECT: LIGO/Virgo G288732: Swift/UVOT follow up of the possible LAT counterpart DATE: 17/06/09 16:13:55 GMT FROM: Samantha Oates at U of Warwick S.W.K. Emery (UCL-MSSL), S.R. Oates (Uni. of Warwick), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano(INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), P.A. Evans (U. Leicester), P. Giommi (ASI), C. Gronwall (PSU), J.A. Kennea (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester), J.A. Nousek (PSU), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: The Swift/UVOT performed a four-pointing follow up of the possible LAT source in the error region of GW trigger G288732 (Omodei et al., LVC Circ. 21227). The observations currently span from 62.8 ks to 86.3 ks after the LVC trigger. We detect optical sources in the XRT error circles of 'source 3', 'source 6' and 'source 7', but these are also present in the SDSS catalogue and we do not find evidence of fading. Additionally, the XRT error circle for 'source 5' is on the edge of the UVOT detector, but we do not see any optical source in the error circle. We do not find any optical afterglow consistent with the LAT position or 'source 1', 'source 2' and 'source 4' of the XRT follow up of G288732 (Evans et al., GCN Circ. 21233) in the UVOT exposures at more than 3 sigma. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the exposures are: XRT_source Filter T_start(s) T_stop(s) Exp(s) Mag/3sigUL 1 u 63081 85743 1737 > 20.8 2 u 62802 85173 1764 > 20.5 4 u 62942 86261 1710 > 20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the transient (Schlegel et al. 1998).