NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 220428d06h28m25s648098usUT
NOTE: Source region spec. is: 275.8888 -56.2550 3"
NOTE: Used archived uvot source position of 275.88880 -56.25500  3.00
NOTE: position reference is GCN_Notice
NOTE: A UVOT position was reported in GCN_Notice_Wed_27_Apr_22_21:10:55_UT
NOTE: Possible detection in uu at T+340.0
NOTE: Possible detection in wh at T+181.8
NOTE: Possible detection in bb at T+596.0
NOTE: Possible detection in vv at T+1570.0 sum

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

GRB 220427A: Swift/UVOT Upper Limits

M. A. Baer (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 220427A
182 s after the BAT trigger (D'Ai et al., GCN Circ. 31960).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 31962)
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           182          332          147         >17.2
u_FC               340          590          246         >17.7
white              182         1887          431         >18.1
v                  670         1762          136         >18.3
b                  596         1862          136         >18.8
u                  340         1837          354         >18.0
w1                 719         1811          117         >20.1
m2                 694         1614           97         >19.1
w2                 646         1912          156         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.097 in the direction of the burst
(Schlegel et al. 1998).


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

GRB 220427A: Swift/UVOT Detection

M. A. Baer (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 220427A
182 s after the BAT trigger (D'Ai et al., GCN Circ. 31960).
A source consistent with the XRT position
(Goad et al. GCN Circ. 31962)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  18:23:33.32 = 275.88885 (deg.)
    Dec (J2000) = -56:15:18.5  = -56.25513 (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              182          332          147         17.32 +/- 0.03
v                  670         1762          136         18.96 +/- 0.28
b                  596          788           39         18.52 +/- 0.18
u                  340          590          246         17.92 +/- 0.07
w1                 719         1811          117        >20.1
m2                 694         1614           97        >19.1
w2                 646         1912          156        >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.097 in the direction of the burst
(Schlegel et al. 1998).