NOTE: uvot_fluxes_wget.pl vrs. 2024-08-27 fem at 250129d03h54m05s846345usUT
NOTE: Source region spec. is: 231.42550 -0.53950 4"
NOTE: Used archived XRT position of 231.42550  -0.53950  4.00
NOTE: position reference is GRB_Auto_Processing

=========== Draft Upper Limit Circular ========

GRB 250128B: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250128B
83 s after the BAT trigger (Evans et al., GCN Circ. 39058).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GRB_Auto_Processing ***
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_FC            83          233          147         >20.7
u_FC               295          545          246         >19.7
white               83         1541          392         >20.9
v                  626         1591          117         >19.2
b                  550         1517           97         >19.3
u                  295         1492          324         >19.9
w1                 675         1468           78         >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.121 in the direction of the burst
(Schlegel et al. 1998).