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GCN Circular 33512

Subject
GRB 230322B: Swift/UVOT Detection
Date
2023-03-23T13:58:42Z (a year ago)
From
Samantha Oates at MSSL <samantha.oates@alumni.ucl.ac.uk>
S. R. Oates (U. of Birmingham) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230322B
119 s after the BAT trigger (Cenko et al., GCN Circ. 33505).
A source consistent with the XRT position
(Evans et al. GCN Circ. 33507)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  01:06:12.84 =  16.55350 (deg.)
    Dec (J2000) = -47:42:02.8  = -47.70079 (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              119          269          147         17.60 +/- 0.04
v                  661         1061           58        >18.3
b                  758          778           19         18.55 +/- 0.36
u                  332          581          246         17.63 +/- 0.08
w1                 710         1095           19         16.90 +/- 0.28
m2                1064         1084           19         17.17 +/- 0.35
w2                 635          655           19         17.36 +/- 0.32

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.017 in the direction of the burst
(Schlegel et al. 1998).
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