NOTE: uvot_fluxes_wget.pl vrs. 2024-08-27 fem at 250109d01h58m33s659988usUT
NOTE: Source region spec. is: 201.32654 25.61519 4"
NOTE: Used archived XRT position of 201.32654  25.61519  4.00
NOTE: position reference is GCN_Circulars-38848
NOTE: Possible detection in uu at T+274.8

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

GRB 250108B: Swift/UVOT Upper Limits

A. A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250108B
117 s after the BAT trigger (Klingler et al., GCN Circ. 38847).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-38848 ***
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           117          267          147         >20.7
u_FC               275          525          246         >19.2
white              117          980          286         >21.1
v                  604          798           39         >18.4
b                  530          723           39         >19.2
u                  275          872          285         >19.2
w1                 654          848           39         >18.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.012 in the direction of the burst
(Schlegel et al. 1998).


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

GRB 250108B: Swift/UVOT Detection

A. A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250108B
117 s after the BAT trigger (Klingler et al., GCN Circ. 38847).
A source consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-38848 ***
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              117          980          286        >21.1
v                  604          798           39        >18.4
b                  530          723           39        >19.2
u                  275          872          285         19.73 +/- 0.23
w1                 654          848           39        >18.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.012 in the direction of the burst
(Schlegel et al. 1998).