GCN Circular 43145
Subject
GRB 251215A: Swift/UVOT Upper LImits
Event
Date
2025-12-16T18:52:06Z (a day ago)
From
S. R. Oates at Lancaster University <samantha.oates@ucl.ac.uk>
Via
email
S. R. Oates (Lancaster U.) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251215A
32 ks after the Fermi/GBM trigger (Fermi GBM team, GCN Circ. 43104).
No optical afterglow is found in the initial UVOT exposures. The UVOT
exposures include the positions of XRT sources 2, 5, 6 and 8
(Osborne et al., GCN 43137). The positions of XRT sources 2, 6, and 8
are consistent with known USNO-B1 sources. No optical source is found
consistent with XRT source 5.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag/3sigUL
white 31995 49531 4297 >22.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the significant reddening of E(B-V) = 0.87 in the direction of the
burst (Schlegel et al. 1998).