NOTE: uvot_fluxes_wget.pl vrs. 2018-11-07 fem at 200901d16h23m02s220644usUT
NOTE: Source region spec. is: 217.85913 -38.71147 4"
NOTE: Used archived XRT position of 217.85913 -38.71147  4.00
NOTE: position reference is GCN_Circulars-28339
NOTE: Possible detection in uu at T+175.8

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

GRB 200901B: Swift/UVOT Upper Limits

A. A. Breeveld (UCL-MSSL) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200901B
176 s after the BAT trigger (Sbarufatti et al., GCN Circ. 28337).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 28339)
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               176          426          246         >18.7
v                  482          801           58         >18.3
b                  431          750           58         >18.8
u                  176          964          391         >18.7
w1                 531          851           58         >17.8
m2                 506          826           58         >17.5
w2                 457          776           58         >17.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.09 in the direction of the burst
(Schlegel et al. 1998).


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

GRB 200901B: Swift/UVOT Detection

A. A. Breeveld (UCL-MSSL) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200901B
176 s after the BAT trigger (Sbarufatti et al., GCN Circ. 28337).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 28339)
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

v                  482          801           58        >18.3
b                  431          750           58        >18.8
u                  176          575          265         19.12 +/- 0.19
w1                 531          851           58        >17.8
m2                 506          826           58        >17.5
w2                 457          776           58        >17.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.09 in the direction of the burst
(Schlegel et al. 1998).