TITLE:   GCN CIRCULAR
NUMBER:  36562
SUBJECT: GRB 240529A: Swift/UVOT Detection
DATE:    24/05/29 13:07:35 GMT
FROM:    Sam Shilling at Lancaster University <shilling.sam@gmail.com>

S.P.R. Shilling (Lancaster U.) and Eyles-Ferris (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 240529A
128 s after the BAT trigger (Eyles-Ferris et al., GCN Circ. 36556).
A source consistent with the enhanced XRT position
(Osborne et al., GCN Circ. 36557) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  22:21:25.97 = 335.35822 (deg.)
    Dec (J2000) = +51:33:43.0  =  51.56194 (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              128          278          147         17.07 +/- 0.04
v                  671          691           19         16.16 +/- 0.14
b                  598          617           19         17.44 +/- 0.16
u                  341          591          246         18.27 +/- 0.10
w1                 720         1642           97        >18.8
m2                 695         1617           97        >18.7
w2                 647         1568          117        >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.332 in the direction of the burst
(Schlegel et al. 1998).