TITLE: GCN CIRCULAR NUMBER: 40747 SUBJECT: GRB 250615A: Swift/UVOT Upper Limits DATE: 25/06/16 11:38:35 GMT FROM: Paul Kuin at MSSL npkuin@gmail.com
N.P.M.Kuin (UCL/MSSL) and S. Dichiara (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250615A 152 s after the BAT trigger (Dichiara et al., GCN Circ. 40736). No optical afterglow consistent with the enhanced XRT position (Goad et al., GCN Circ. 40739) is detected in the initial UVOT exposures. 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
u_FC 152 402 246 >19.8 white 432 1722 284 >21.0 v 483 1772 156 >19.5 b 408 1697 136 >20.7 u 152 1672 363 >20.0 w1 532 1821 136 >19.5 w2 804 1747 78 >19.2
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.165 in the direction of the burst (Schlegel et al. 1998).
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