TITLE:   GCN CIRCULAR
NUMBER:  27352
SUBJECT: GRB 200306C: Swift/UVOT Detection
DATE:    20/03/09 06:03:35 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

 GRB 200306C: Swift/UVOT Detection

J. D. Gropp (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200306C
118 s after the BAT trigger (Gropp et al., GCN Circ. 27326).

A fading source consistent with the positions reported by
FRAM-ORM (Jelinek et al., GCN Circ. 27238),
BOOTES-1 (Hu et al., GCN Circ. 27329),
SAO RAS (Moskvitin et al., GCN Circ. 27333)
Liverpool Telescope (Izzo et al., GCN Circ 27334)
and OSN (Kann et al., GCN Circ. 27335)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  13:14:13.46 = 198.55607 (deg.)
    Dec (J2000) = +11:16:11.7  =  11.26992 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).

Preliminary detections 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

u_fc           141             390               245
16.90+-0.05
u                899           1049               147
18.39+-0.16


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).