TITLE: GCN CIRCULAR NUMBER: 38350 SUBJECT: LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits DATE: 24/11/27 16:50:48 GMT FROM: N. Klingler at NASA-GSFC/UMBC/CRESST II <noelklingler@gmail.com> N.J. Klingler (NASA-GSFC / UMBC / CRESST II), S.R. Oates (Lancaster U.), A. Tohuvavohu (U. Toronto), A.A. Breeveld (UCL-MSSL), C. Gronwall (PSU), N.P.M. Kuin (UCL-MSSL), F.E. Marshall (NASA-GSFC), 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), and E. Troja (U. Tor Vergata, INAF) report on behalf of the Swift Team: Swift has carried out observations of the error region of the BAT-GUANO candidate counterpart, which was detected 11.2641 s after T0 of S241125n (DeLaunay et al., GCN Circ. 38308).  Swift-UVOT observations were carried out using the White filter for a total of 4.8 ks, spanning from 55 ks to 74 ks after the LVC trigger.   No new/uncatalogued sources were detected within the BAT-GUANO localization (RA, Dec = 58.079, +69.689 deg, r=5', 50% containment; GCN Circ. 38308), with an average 3sigma limit on the magnitude >23.2 (AB; White filter). As reported by Evans et al. (GCN Circ. 38324), 5 X-ray sources were seen.  However, none of these sources were detected with UVOT.  S241125n_X1 and S241125n_X2 were located outside of UVOT's field of view.  S241125n_X3 was not detected, with a 3sigma limit on the magnitude (AB) >23.16.  S241125n_X4's position was heavily contaminated by image artifacts and coincidence loss from a bright nearby source.  S241125n_X5 was not detected, though its position was also affected by an image artifact from a bright nearby source, though to a lesser degree.  The precise upper limit at this location can not be accurately determined, but can be approximated as >23. This circular is an official data product of the Swift-UVOT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/38350. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...