GCN Circular 30619

GRB 210807C: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210807C
180 s after the BAT trigger (Lien et al., GCN Circ. 30610
Not found
 
 
).
No optical afterglow consistent with the XRT position
(Lien et al. GCN Circ. 30610
Not found
 
 
)
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 initial exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

v                  180          852          596         >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 3.076 in the direction of the burst
(Schlegel et al. 1998).