GCN Circular 19357
Subject
GRB 160425A: Swift/UVOT Detection
Date
2016-04-27T20:10:02Z (8 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) and H. A. Krimm (CRESST/GSFC/USRA)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160425A
208 s after the BAT trigger (Krimm et al., GCN Circ. 19343).
A fading source consistent with the XRT position (Beardmore et al. GCN Circ. 19347)
is detected in the initial UVOT exposures. This source is consistent
with the optical transient reported by MASTER (Lipunov et al, GCN Circ. 19344)
and GROND (Bodensteiner et al., GCN Circ. 19349). The source has plateaud over
the last day, which may indicate detection of the host galaxy reported
by MASTER (Balanutsa et al., GCN Circ. 19351).
The preliminary UVOT position is:
RA (J2000) = 18:41:18.58 = 280.32743 (deg.)
Dec (J2000) = -54:21:36.3 = -54.36007 (deg.)
with an estimated uncertainty of 0.53 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 (fc) 208 358 147 19.57 +/- 0.10
white 859 1009 147 20.70 +/- 0.35
white 1164 2397 155 >20.19
white 6727 8221 254 >20.79
white 11858 12765 885 21.03 +/- 0.19
white 35282 41433 2162 21.48 +/- 0.23
white 46310 58620 3898 21.48 +/- 0.16
white 104099 111153 2061 21.80 +/- 0.30
v 365 2447 233 19.22 +/- 0.31
b 465 1852 156 20.16 +/- 0.32
u 440 6517 410 20.07 +/- 0.26
w1 415 7748 607 20.24 +/- 0.30
m2 390 7542 430 >19.7
w2 515 13672 1296 >20.8
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).