NOTE: uvot_fluxes_wget.pl vrs. 2024-08-27 fem at 250321d06h24m01s005184usUT
NOTE: Source region spec. is: 295.077 +21.041 3"
NOTE: Used archived BAT position of 295.07700  21.04100
NOTE: position reference is GCN_Position_Notice

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

GRB 250321A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and Gupta (NASA GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250321A
128 s after the BAT trigger (Gupta et al., GCN Circ. 39794).
No optical afterglow consistent with the BAT position
*** POSITION REFERENCE is GCN_Position_Notice ***
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           128          278          147         >19.9
white              128         4071          344         >20.6
v                 4282         4482          197         >18.9
b                 3667         5142          236         >19.9
u                  340         5097          232         >19.3
w1                4693         4892          197         >19.4
m2                4487         4687          197         >19.5
w2                4077         4277          197         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 4.368 in the direction of the burst
(Schlegel et al. 1998).