  We present results of polarimetric, photometric, and spectral observations of
the near-Earth asteroid (3200) Phaethon carried out at the 6-m BTA telescope of
the Special Astrophysical Observatory and the 2.6-m and 1.25-m telescopes of
the Crimean Astrophysical Observatory over a wide range of phase angles during
its close approach to the Earth at the end of 2017 (19-135 deg) and in 2020 at
\alpha = 52.2 deg. Using our and other available in literature data, we found
that the maximum degree of linear polarization of Phaethon in the V band is 45%
at the phase angle 124 deg. Using the dependence (polarimetric slope-albedo) we
have found the geometric albedo of asteroid Phaethon to be 0.06. This value
falls into the lower range of albedo values for asteroids determined by
different methods. The mean color indices U-B=0.207 and B-V=0.639 of the
asteroid are derived at heliocentric and geocentric distances 1.077 au and
0.102 au, respectively. The effective diameter of Phaethon is estimated from
obtained absolute magnitude and geometrical albedo, it is equal to 6.8 km. The
best fit to the observed polarimetric data was obtained with the Sh-matrix
model of conjugated random Gaussian particles composed of Mg-rich silicate
(90%) and amorphous carbon (10%).
