[vsnet-grb-info 19671] GRB 170804A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21415
SUBJECT: GRB 170804A: Swift/UVOT Detection 
DATE:    17/08/04 21:03:59 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (U. Warwick) and A. Cholden-Brown (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170804A
132 s after the BAT trigger (Cholden-Brown et al., GCN Circ. 21410).

A fading source consistent with the XRT position
(Evans et al., GCN Circ. 21413) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
     RA  (J2000) =   0:25:34.29 =   6.39288 (deg.)
     Dec (J2000) = -64:47:03.1  = -64.78419 (deg.)

with an estimated uncertainty of 0.5 arc sec. (radius, 90% confidence).

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
white_FC         132          281           147         18.9 +/- 0.1
white            871          1020          147         20.0 +/- 0.2
u_FC             289          539           246         18.7 +/- 0.1
v         796          1243           58         >18.7
b                545          565            19         18.9 +/- 0.4
uvw1             671          1292           78         >19.0
uvw2             596          1392           97         >19.2


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).








---------------------------------------------

Dr Samantha Oates

Leverhulme Early Career Fellow
Department of Physics
University of Warwick
Coventry
CV4, UK
Tel:  +44 (024) 765 23383
Email: s.oates at warwick.ac.uk<mailto:s.oates at warwick.ac.uk>
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