NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 210321d16h40m57s528181usUT
NOTE: Source region spec. is: 87.8947 +70.1305 3"
NOTE: Used archived uvot source position of  87.89470  70.13050  3.00
NOTE: position reference is GCN_Notice
NOTE: A UVOT position was reported in GCN_Notice_Sun_21_Mar_21_08:09:02_UT
NOTE: Possible detection in uu at T+3506.7
NOTE: Possible detection in wh at T+2735.2
NOTE: Possible detection in bb at T+3713.1
NOTE: Possible detection in w1 at T+3301.8
NOTE: Possible detection in vv at T+2891.9

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

GRB 210321A: Swift/UVOT Upper Limits

S. J. Laporte (PSU) and S. Dichiara (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210321A
2735 s after the BAT trigger (Dichiara et al., GCN Circ. 29677).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 29681)
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          2735         2885          147         >18.4
white             2735         4118          344         >18.5
v                 2892         4465          331         >18.0
b                 3713         3913          197         >18.3
u                 3507         3706          197         >17.9
w1                3302         3502          197         >18.0
m2                3097         3296          197         >18.9
w2                4124         4324          197         >19.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.118 in the direction of the burst
(Schlegel et al. 1998).


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

GRB 210321A: Swift/UVOT Detection

S. J. Laporte (PSU) and S. Dichiara (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210321A
2735 s after the BAT trigger (Dichiara et al., GCN Circ. 29677).
A source consistent with the XRT position
(Beardmore et al. GCN Circ. 29681)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  05:51:34.75 =  87.89479 (deg.)
    Dec (J2000) = +70:07:49.8  =  70.13051 (deg.)
with an estimated uncertainty of 0.49 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             2735         2885          147         18.69 +/- 0.09
v                 2892         4465          331         18.44 +/- 0.16
b                 3713         3913          197         18.64 +/- 0.11
u                 3507         3706          197         18.29 +/- 0.12
w1                3302         3502          197         18.48 +/- 0.17
m2                3097         3296          197        >18.9
w2                4124         4324          197        >19.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.118 in the direction of the burst
(Schlegel et al. 1998).