[vsnet-grb-info 19402] GRB170519A, Swift-UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21118
SUBJECT: GRB170519A, Swift-UVOT Detection
DATE:    17/05/19 23:24:09 GMT
FROM:    Sam LaPorte at PSU  <sjl5346 at psu.edu>

GRB 170519A: Swift/UVOT Detection

S. J. LaPorte (PSU) and T. N. Ukwatta (LANL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170519A
93 s after the BAT trigger (Ukwatta et al., GCN Circ. 21106).
A fading source consistent with the XRT position
(Beardmore et al. GCN Circ. 21107)
is detected in all initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  10:53:42.45 = 163.42688 (deg.)
    Dec (J2000) = +25:22:27.5  =  25.37431 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

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              5315          5515         196          17.22+-0.03  
white               582           773          38          16.25+-0.04
white                89           239         147          16.91+-0.03
v                    68          5926         421          17.46+-0.08  
b                   557          6594         282          17.66+-0.05
u                   302           552         245          16.00+-0.04   
uvw1                680          6337         412          16.76+-0.05 
uvm2               5932          6131         196          17.13+-0.11   
uvw2                607           627          19          16.45+-0.20  

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