NOTE: uvot_fluxes_wget.pl vrs. 2024-08-27 fem at 250905d01h41m55s463058usUT
NOTE: Source region spec. is: 84.38046 3.58444 4"
NOTE: Used archived XRT position of  84.38046   3.58444  4.00
NOTE: position reference is GCN_Circulars-41711
NOTE: Possible detection in wh at T+85.7

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

GRB 250904A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and C. Salvaggio (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250904A
86 s after the BAT trigger (Salvaggio et al., GCN Circ. 41704).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-41711 ***
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            86          235          147         >19.5
white               86          235          147         >19.5
u                  298          441          141         >18.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.305 in the direction of the burst
(Schlegel et al. 1998).


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

GRB 250904A: Swift/UVOT Detection

***UBS*** (***INSTITUTION***) and C. Salvaggio (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250904A
86 s after the BAT trigger (Salvaggio et al., GCN Circ. 41704).
A source consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-41711 ***
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               86          235          147         20.12 +/- 0.25
u                  298          441          141        >18.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.305 in the direction of the burst
(Schlegel et al. 1998).