3U 1809 +50. Lx(soft)/Lopt ~15.
Emissions of H and KCaII, H, HeI, HeII, etc.
In the spectrum. Epoch of Min I in V light is given.
The period shows complex variations. The phase of Min I
in U light is 0.30p, in B 0.15P, in R 0.05P. Min I is
probably due to an eclipse of a hot spot and the gas flow
near the surface of the white dwarf by the white dwarf
itself. The depth of Min I is up to 0.7m. Min II with the
depth up to 0.4m (sometimes absent), Min II - Min I = 0.55P.
Min II coincides in phase with the X-ray eclipse.
"High and low states (b ~13.0m and B ~15.0m on average)
in the high state there are variations with Delta(m) ~0.3m
"on the time scale >= 200d
130d - 700d  or less. During low states the
depth of minima is small. Flickering up to 0.8mV in
"several minutes or dozens of seconds
on the time scale of ~10s not correlating with
optical flickering. The magnetic field ~1*10**7 G at
the equator, ~2*10**7 G on poles. Variable circular
(from +3% to -9%) and linear (up to 7%) polarization.
IR excess at lambda 10 mkm.