GCN Circular 45700
GRB 260922A: Swift/UVOT Upper Limits
From: unknown
Issued: 2026-09-23 06:26 UTC
Type: GRB, Optical Transient

S. P. R. Shilling (Lancaster U.) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 260922A
118.5 s after the BAT trigger (Page et al., GCN Circ. 45690).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circ. 45696) 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

white_FC 118 268 147 >20.2
white 118 4697 530 >20.8
v 661 1062 58 >18.3
b 587 1161 58 >19.2
u_FC 331 581 246 >19.7
u 331 1135 285 >19.8
w1 710 1111 19 >18.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.035 in the direction of the burst
(Schlegel et al. 1998).

Filter: gamma-ray bursts are posted only if in the top 10% of the past year's — by fluence (total energy received per cm², from Fermi GBM, Konus-Wind, GECAM and similar circulars; now ≥ 3.9×10^-5 erg/cm²) or by the number of GCN Circulars about the burst (now ≥ 14). Thresholds are recalculated monthly.
Relayed automatically from NASA's General Coordinates Network.