GCN Circular 18856
Subject
GRB 160104A: Swift/UVOT Detection
Date
2016-01-12T22:20:40Z (8 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F.E. Marshall (NASA/GSFC) and A. Melandri (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160104A
85 s after the BAT trigger (Melandri et al., GCN Circ. 18815).
A fading source consistent with the XRT position (Beardmore et al. GCN Circ. 18821)
and the optical afterglow position (Guidorzi et al. GCN Circ. 18816)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 05:07:11.05 = 76.79603 (deg.)
Dec (J2000) = 11:19:25.5 = 11.32375 (deg.)
with an estimated uncertainty of 0.64 arc sec. (radius, 90% confidence).
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 85 235 141 20.48 +/- 0.22
white 1180 1893 94 >20.5
v 627 1252 78 18.92 +/- 0.32
b 553 1869 136 >19.8
u 297 1843 363 >20.5
w1 677 1819 136 >20.1
m2 825 5587 203 >20.1
w2 602 5249 333 >20.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.26 in the direction of the burst
(Schlegel et al. 1998).