GCN Circular 45819
Subject
GRB 261005B: Swift/UVOT Upper Limits
Event
Date
2026-10-06T13:43:34Z (7 hours ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
Via
email
A. A. Breeveld (UCL-MSSL), N. Klingler (NASA-GSFC/UMBC/CRESST II) and T.M. Parsotan (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT started observing the field of GRB 261005B 4424 s after the BAT trigger (Parsotan et al., GCN Circ. 45812).
No optical afterglow consistent with the enhanced XRT position (Page et al., GCN Circ. 45815) 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 data available are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 5451 5651 197 >20.4
b 5247 5446 197 >19.8
u 5040 5239 197 >19.3
v 4424 4624 197 >18.3
uvw1 4835 5035 197 >18.7
uvw2 5658 5836 175 >19.1
uvm2 4629 4829 197 >18.1
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.12 in the direction of the burst (Schlegel et al. 1998).