TITLE:   GCN CIRCULAR
NUMBER:  23400
SUBJECT: GRB 181030A: Swift/UVOT Detection
DATE:    18/10/31 13:40:13 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and E. Sonbas (Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181030A
152 s after the BAT trigger (Sonbas et al., GCN Circ. 23389).
A fading source is detected in the initial UVOT exposures at a position
consistent with the XRT position (Beardmore et al., GCN Circ. 23391) and
also with SAO RAS (Moskvitin et al., GCN Circ. 23390) and MASTER Net
(Lipunov et al., GCN Circ. 23392).

Preliminary detections and 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           152          270          116        19.34 +/- 0.30
white             3978         5614          393        >20.7
v                 4389         6009          378        >18.9
b                 3774        17487          635        >20.1
u                 3569        17236         1278        >20.3
uvw1              4799        11747          852        >20.2
uvm2              4594        22498         1201        >20.7
uvw2              4184         5819          393        >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).