[vsnet-grb-info 15548] GRB 140919A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16837
SUBJECT: GRB 140919A: Swift/UVOT Detection
DATE:    14/09/20 11:53:48 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC/UCL-MSSL) and M.E. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140919A
3125 s after the BAT trigger (Gropp et al., GCN Circ. 16831).
A fading source consistent with the optical and enhanced XRT position
(Schmidl et al. GCN Circ. 16836; Beardmore et al., GCN Circ 16834)
is detected in the initial UVOT exposures. Initial identification 
was complicated by the presence of a point source in the 
DSS close to the optical position. Photometry is therefore also 
complicated by the presence of this point source. 

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

white(FC)         3125         3275          147         16.62 +/- 0.05
white            45180        45480          295         19.40 +/- 0.11
v                 4848         5047          197         17.33 +/- 0.10
b                 8834         9134          295         18.34 +/- 0.09
u                 5462         5613          148         16.86 +/- 0.07
w1                5258         5458          197         16.98 +/- 0.09
m2                5052         5252          197         17.12 +/- 0.11

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.09 in the direction of the burst
(Schlegel et al. 1998).