GCN Circular 16130

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
Not found
 
 
).
Optical and IR photometry and positions were reported, as well as a redshift
(Cenko, et al., GCN Circ. 16129
Not found
 
 
; Hentunen et al., GCN Circ. 16126
Not found
 
 
; Tanvir
et
al., GCN Circ. 16125
Not found
 
 
; Kuin et al., GCN Circ. 16123
Not found
 
 
; Butler et al., GCN
Circ.
16121
Not found
 
 
; Guver et al., GCN Circ. 16120
Not found
 
 
; and Zheng et al., GCN Circ. 16119
Not found
 
 
.)
 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).