TITLE: GCN CIRCULAR NUMBER: 12355 SUBJECT: GRB 110915A: Swift/UVOT Upper Limits DATE: 11/09/17 20:18:06 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten (PSU) and S. T. Holland (CRESST/USRA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110915A 84 ks after the BAT trigger (Holland et al., GCN Circ. 12335). No optical afterglow consistent with the enhanced XRT position (Evans et al., GCN Circ. 12340) is detected in the initial UVOT exposures. UVOT magnitude 3-sigma upper limits are reported in the following table: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white 84 1884 429 > 21.46 v 616 5316 203 > 19.35 b 540 1858 136 > 20.10 u 284 1834 362 > 20.36 uvw1 665 1809 136 > 19.59 uvm2 641 1784 136 > 19.46 uvw2 592 1897 144 > 19.82 The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.06 (Schlegel et al. 1998). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).