TITLE:   GCN CIRCULAR
NUMBER:  34643
SUBJECT: GRB 230906A: Swift/UVOT Upper Limits
DATE:    23/09/09 10:53:16 GMT
FROM:    Samantha Oates at University of Birmingham <samantha.oates@alumni.ucl.ac.uk>

S. R. Oates (Lancaster U. ) and M. J. Moss (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230906A
93 ks after IPN-detection (Kozyrev et al., GCN Circ 34637). No optical
afterglow consistent with the XRT position  (Beardmore et al., GCN
Circulars 34639), 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            93297        106009        4648          >22.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.021 in the direction of the burst
(Schlegel et al. 1998).