GCN Circular 17933
Subject
V404 Cyg: Swift/UVOT Detection
Date
2015-06-16T15:01:12Z (10 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (IAA-CSIC/UCL-MSSL) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of V404 Cyg
184 s after the BAT trigger (Barthelmy et al., GCN Circ. 17929).
A source consistent with the XRT position is detected in the initial
UVOT exposures. The white filter is approximately constant for
the first 600s after the trigger, but a slight increase in flux is observed
in white after this time until observations cease at ~900s. The increase
in flux is also observed in the v and b filters.
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 (FC) 184 334 147 15.72 +/- 0.02
white 875 919 44 15.34 +/- 0.03
v 673 693 19 14.58 +/- 0.07
v 848 867 19 14.22 +/- 0.06
b 599 619 19 16.17 +/- 0.08
b 773 793 19 15.78 +/- 0.07
u (FC) 342 591 246 16.13 +/- 0.04
u 748 768 20 16.06 +/- 0.11
w1 722 742 19 > 17.66
m2 698 717 19 > 17.45
w2 649 843 39 > 18.37
The magnitudes in the table are not corrected for the large Galactic
extinction due to the reddening of E(B-V) = 2.02 in the direction of the burst
(Schlegel et al. 1998).