GCN Circular 37611

A.A. Breeveld (UCL-MSSL), F.E. Marshall (NASA/GSFC), S.R. Oates (Lancaster U.), N.P.M. Kuin (UCL-MSSL), C. Gronwall (PSU), N.J. Klingler (NASA/GSFC UMBC CRESST II), M. De Pasquale (University of Messina), M.J. Page (UCL-MSSL), S. Shilling (Lancaster U.), M.H. Siegel (PSU), A. D’Aì (INAF-IASFPA), P. D’Avanzo (INAF-OAB), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), J.J. Delaunay (PSU), S. Dichiara (PSU), V. D’Elia (ASI-SSDC & INAF-OAR), R.A.J.Eyles-Ferris (U. Leicester), P.A. Evans (U. Leicester), R. Gayathri (PSU), D. Hartmann (Clemson University), J.A. Kennea (PSU), S. Laha (NASA/GSFC), H.A. Krimm (NSF), D. B. Malesani (DTU Space), P. O’Brien (U. Leicester), J.P. Osborne (U. Leicester), T. Partosan (NASA/GSFC), M. Perri (ASDC),K.L. Page (U. Leicester), D.M. Palmer (LANL), S. Ronchini (PSU), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), G. Tagliaferri (INAF-OAB), E. Troja (U. Tor Vergata, INAF), A. Tohuvavohu (U. Toronto) on behalf of the Swift team:

We report on the analysis of the Swift UVOT follow-up of two GW events S240915b and S240919bn.
The procedure of the UVOT follow-up has been described in Oates et al.,2021, MNRAS, 507, 12960.

We examined the UVOT data for all fields pointed at by Swift through the planned tiling exposures (310 for S240915b; 217 for S240919bn) in either the U or UVW1 band. The exposures were typically around 70s long and reached upper limits around 19-19.3 in U and 18.2-18.7 in UVW1.

No credible candidates associated with S240915b or S240919bn were identified.