[vsnet-grb-info 14816] GRB 140419A: Swift UVOT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16130
SUBJECT: GRB 140419A: Swift UVOT refined analysis
DATE:    14/04/19 21:55:33 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

N. P. M. Kuin (UCL-MSSL) and F. E. Marshall (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140419A
97 s after the BAT trigger (Marshall et al. GCN Circ. 16118).
Optical and IR photometry and positions were reported, as well as a redshift
(Cenko, et al., GCN Circ. 16129; Hentunen et al., GCN Circ. 16126; Tanvir
et
al., GCN Circ. 16125; Kuin et al., GCN Circ. 16123; Butler et al., GCN
Circ.
16121; Guver et al., GCN Circ. 16120; and Zheng et al., GCN Circ. 16119.)
 A source consistent with the XRT position is detected in the initial UVOT
exposures.

The preliminary UVOT position is:
    RA  (J2000) =  08:27:57.56 = 126.98982 (deg.)
    Dec (J2000) = +46:14:25.3  =  46.24037 (deg.)
with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence).

Due to the GRB lying on the edge of a large scattered light feature from
the
bright star nearby, photometry errors are large until a good background
template can be made at late times.
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          246          147         16.2 +/- 0.2
v                  638          658           19         16.1 +/- 0.2
b                  564          756           39         18.4 +/- 0.2
u                  309         2003          362        >21.0
w1                 687          707           19        >18.1

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).