GCN Circular 25972

GRB 191004A: Swift/UVOT Detection

S. J. LaPorte (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 191004A
84 s after the BAT trigger (Cenko et al., GCN Circ. 25945
Not found
 
 
).
A fading source consistent with the XRT position
(Osborne et al. GCN Circ. 25950
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 first
finding chart (FC) exposure and subsequent exposures are:

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

b                       582             775             38         >18.83
uvm2                680             873             38         >18.00
u                       327             750           265         >19.60
v                       656            1104            58         >18.06
uvw1                705              898            38         >17.89
uvw2                632            1080            58         >18.28
white                115            1054          333           19.78+-0.16

white              5567          12438          956         >21.24

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).