TITLE:   GCN CIRCULAR
NUMBER:  43145
SUBJECT: GRB 251215A: Swift/UVOT Upper LImits
DATE:    25/12/16 18:52:06 GMT
FROM:    S. R. Oates at Lancaster University <samantha.oates@ucl.ac.uk>

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).