NOTE: uvot_fluxes_wget.pl vrs. 2024-08-27 fem at 250505d20h14m17s669954usUT
NOTE: Source region spec. is: 269.61808 -40.36675 4"
NOTE: Used archived XRT position of 269.61808 -40.36675  4.00
NOTE: position reference is GCN_Circulars-40345
NOTE: Possible detection in uu at T+137.4
NOTE: Possible detection in wh at T+5098.8 sum

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

GRB 250504A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and M. J. Moss (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250504A
137 s after the BAT trigger (Moss et al., GCN Circ. 40343).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-40345 ***
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

u_FC               137          387          246         >18.7
white              417         5299          255         >19.8
v                  467         5709          255         >19.2
b                  393          760           58         >18.7
u                  137          735          285         >18.8
w1                 516         6004          123         >19.0
m2                 492         5914          255         >19.7
w2                 443         5504          255         >20.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.191 in the direction of the burst
(Schlegel et al. 1998).


=========== Draft Detection Circular ========

GRB 250504A: Swift/UVOT Detection

***UBS*** (***INSTITUTION***) and M. J. Moss (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250504A
137 s after the BAT trigger (Moss et al., GCN Circ. 40343).
A source consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-40345 ***
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

white              417         5299          255         20.46 +/- 0.27
v                  467         5709          255        >19.2
b                  393          760           58        >18.7
u                  137          387          246         19.36 +/- 0.27
w1                 516         6004          123        >19.0
m2                 492         5914          255        >19.7
w2                 443         5504          255        >20.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.191 in the direction of the burst
(Schlegel et al. 1998).