[vsnet-alert 22723] Re: Swift J1858.6-0814: violent optical variability in a black-hole binary

[mkimura]

This is additional information.
A. Sosnovskij and E. Pavlenko performed optical photometry of this target
at 2.6-m telescope with 7-s exposure time in R band on November 7th.
They found rapid variability shown in the attached figure.  The amplitude
was ~1.2 magnitude.  This kind of high-amplitude variations could be
detected with ~1-min exposure time.
In addition, they reported that variability has been seen since November 
4th.

Thanks,
Mariko


On 2018/11/13 0:44, mkimura wrote:
> 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
>