NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 210412d09h00m27s949544usUT
NOTE: Source region spec. is: 296.61178 -39.39774 3"
NOTE: Used archived uvot source position of 296.61178 -39.39774  3.00
NOTE: position reference is GCN_Circ_29794
NOTE: A UVOT position was reported in GCN_Circ_29794
NOTE: Possible detection in uu at T+278.6
NOTE: Possible detection in wh at T+66.4
NOTE: Possible detection in bb at T+534.9
NOTE: Possible detection in vv at T+608.8

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

GRB 210411C: Swift/UVOT Upper Limits

N. P. M. Kuin (UCL-MSSL) and Sbarrato (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210411C
66 s after the BAT trigger (Sbarrato et al., GCN Circ. 29794).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 29800)
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            66          216          147         >17.1
u_FC               279          528          246         >17.6
white               66         1353          373         >17.7
v                  609         5806          270         >18.1
b                  535         1329           78         >17.8
u                  279         1304          304         >17.7
w1                 658         1280           78         >19.7
m2                 633         5836           83         >19.6
w2                 584         5600          255         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.081 in the direction of the burst
(Schlegel et al. 1998).


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

GRB 210411C: Swift/UVOT Detection

N. P. M. Kuin (UCL-MSSL) and Sbarrato (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210411C
66 s after the BAT trigger (Sbarrato et al., GCN Circ. 29794).
A source consistent with the XRT position
(Goad et al. GCN Circ. 29800)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  19:46:26.81 = 296.61170 (deg.)
    Dec (J2000) = -39:23:52.2  = -39.39784 (deg.)
with an estimated uncertainty of 0.43 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

white               66          216          147         17.16 +/- 0.03
v                  609          801           39         17.43 +/- 0.18
b                  535          555           20         17.82 +/- 0.17
u                  279          528          246         17.82 +/- 0.07
w1                 658         1280           78        >19.7
m2                 633         5836           83        >19.6
w2                 584         5600          255        >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.081 in the direction of the burst
(Schlegel et al. 1998).