[vsnet-outburst 22923] Swift J1858.6-0814: violent optical variability in a black-hole binary

[mkimura]

Swift J1858.6-0814: violent optical variability in a black-hole binary

     According to the recent ATELs (#12614, #12180, #12186, #12197),
the newly discovered X-ray transient source called Swift J1858.6-0814
likely has a black hole, and it showed large-amplitude (~2 mag) and
short-term (~ several seconds) optical variability.
(e.g., https://www.dropbox.com/s/tllzn0fgag6ittm/SwiftJ1858.jpg?dl=0
         http://www.southampton.ac.uk/~pg3e14/swiftj1858/ )
Some people pointed out that the variability may be similar to
V404 Cyg, one of the most famous black-hole X-ray binaries
because of the optical color variations and flaring events.
It is unclear if the system is still bright, but detailed observations
will be interesting.
The magnitude was 16.3-18.1 mag in r' band on November 6th.
The coordinate of this object is as follows:
RA(J2000) = 18:58:34.893
DEC(J2000) = -08:14:14.938