TITLE:   GCN CIRCULAR
NUMBER:  17580
SUBJECT: GRB 150314A: Swift/UVOT Detection
DATE:    15/03/14 18:04:29 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

L. M. Z. Hagen (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150314A
95 s after the BAT trigger (Hagen et al., GCN Circ. 17573). We detect
a fading source consistent with the XRT position (Beardmore et al.
GCN Circ. 17575) and optical detections (Zheng & Filippenko GCN Circ.
17574, Trotter et al. GCN Circ. 17577) that is detected in all but the
bluest UVOT filters.

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               97          244          144         17.22 +/- 0.03
white              587          781           38         19.13 +/- 0.18
white             5472         5671          196        >21.02
v                   75           85            9         15.48 +/- 0.13
v                  637          657           19         17.75 +/- 0.33
v                 4445         6082          390        >19.77
b                  562          756           38         19.28 +/- 0.35
b                 5266         5466          196        >20.32
u                  307          556          245         18.86 +/- 0.14
u                  712         6528          253        >20.14
uvw1               687         6485          412        >20.31
uvm2              4650         6280          391        >20.16
uvw2               613         5877          412        >20.46

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).