TITLE: GCN CIRCULAR NUMBER: 32785 SUBJECT: GRB 221016A: Swift/UVOT Detection DATE: 22/10/17 20:13:01 GMT FROM: Mike Siegel at PSU/Swift MOC mhs18@psu.edu
M. H. Siegel (PSU) 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 221016A 97 s after the BAT trigger (Page et al., GCN Circ. 32774). A source consistent with the enhanced XRT position (Goad et al. GCN Circ. 32776) is detected in the initial UVOT exposures.
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 97 247 147 20.20 +/- 0.23 b 3736 3861 123 >19.8 u 309 349 39 >18.8
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.026 in the direction of the burst (Schlegel et al. 1998).