[vsnet-outburst 25963] Re: [vsnet-chat 8510] MGAB-V859 - a peculiar ER Ursae Majoris variable with a long standstill?

[Taichi Kato]

Re: [vsnet-chat 8510] MGAB-V859 - a peculiar ER Ursae Majoris variable with a long standstill?

See http://ooruri.kusastro.kyoto-u.ac.jp/mailarchive/vsnet-chat/8510

MGAB-V859 was discovered in October 2019 during data-mining search for
cataclysmic variables using ZTF DR1 data. It shows typical UGER variability
in the 2018 season (superoutbursts up to g=17.7 mag every 45-50 days with
up to 7 small outbursts between). It is similar in early 2019, however
after the last superoutburst in August 2019, the target had gone completely
to a standstill state. In the next three months, the target remained around
g=18.6 mag and the scatter indicates no variations above 0.5 mag. A hybrid
UGER+UGZ variable?

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   Subsequent observation particularly how the standstill ends
is most important.  In the case of NY Ser, at least one standstill
ended with a superoutburst.

https://ui.adsabs.harvard.edu/abs/2019PASJ...71L...1K/abstract

   This finding was one of the most important ones in
the recent research of the mechanism of dwarf novae.
A new example in MGAB-V859 will be very much appreciated.

   NL / ER UMa transition is also known in BK Lyn, but
how it entered the ER UMa state is unknown.