GCN Circular 26127

GRB 191031C: Swift/UVOT Detection

J. D. Gropp (PSU) and Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 191031C
91 s after the BAT trigger (Ambrosi et al., GCN Circ. 26108
Not found
 
 
).
A source consistent with the XRT position
(Goad et al. GCN Circ. 26115
Not found
 
 
)
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

u                        307           556            245          >19.71
white                   92            242            147            20.27+-0.32
white                 862          1011            147          >20.39


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.17 in the direction of the burst
(Schlegel et al. 1998).