GCN Circular 42055
Subject
GRB 251001B: Swift/UVOT Detection
Event
Date
2025-10-02T12:12:59Z (a month ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
Via
email
A.A. Breeveld (UCL-MSSL), S.P.R. Shilling (Lancaster U.) and A.P. Beardmore (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251001B 119 s after the BAT trigger (Beardmore et al., GCN Circ. 42039). A source consistent with the enhanced XRT position (Beardmore et al., GCN Circ. 42045) and also with the optical counterpart seen by Gompertz et al. (GCN Circ. 42040), An et al. (GCN Circ. 2041), Strausbaugh and Cucchiara (GCN Circ. 42043) and de Ugarte Postigo et al. (GCN Circ. 42050) is detected in the initial UVOT exposures.
Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposures and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 119 269 147 18.76 +/- 0.06
u_FC 331 581 246 18.86 +/- 0.15
white 611 630 10 19.0 +/- 0.25
white 861 1010 147 19.6 +/- 0.2
b 587 779 39 > 19.0
v 661 681 20 > 17.4
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.023 in the direction of the burst (Schlegel et al. 1998).