NOTE: uvot_fluxes_wget.pl vrs. 2018-01-16 fem at 181021d06h07m16s972508usUT
NOTE: Source region spec. is: 13.98240 -47.38105 3"
NOTE: Used archived uvot source position of  13.98240 -47.38105  3.00
NOTE: position reference is GCN_Circ_23349
NOTE: A UVOT position was reported in GCN_Circ_23349
NOTE: Possible detection in uu at T+121.6
NOTE: Possible detection in bb at T+377.1
NOTE: Possible detection in vv at T+428.3

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

GRB 181020A: Swift/UVOT Upper Limits

J. D. Gropp (PSU) and Moss (George Washington University)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181020A
122 s after the BAT trigger (Moss et al., GCN Circ. 23349).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 23351)
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               122          371          246         >17.5
v                  428        24048         1781         >17.4
b                  377        22695         2949         >19.0
u                  122         6823          769         >18.4
w1                 626         6695          432         >20.2
m2                 453         6490          413         >20.3
w2                 701        23602         2873         >21.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).


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

GRB 181020A: Swift/UVOT Detection

J. D. Gropp (PSU) and Moss (George Washington University)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181020A
122 s after the BAT trigger (Moss et al., GCN Circ. 23349).
A source consistent with the XRT position
(Goad et al. GCN Circ. 23351)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  00:55:55.77 =  13.98239 (deg.)
    Dec (J2000) = -47:22:51.9  = -47.38108 (deg.)
with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence).

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                  428          448           20         15.44 +/- 0.09
b                  377          397           19         17.01 +/- 0.11
u                  122          371          246         17.66 +/- 0.06
w1                 626         6695          432        >20.2
m2                 453         6490          413        >20.3
w2                 701        23602         2873        >21.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).