A comprehensive study of the open cluster NGC 6866
  We present CCD $UBVRI$ photometry of the field of the open cluster NGC 6866.
Structural parameters of the cluster are determined utilizing the stellar
density profile of the stars in the field. We calculate the probabilities of
the stars being a physical member of the cluster using their astrometric data
and perform further analyses using only the most probable members. The
reddening and metallicity of the cluster were determined by independent
methods. The LAMOST spectra and the ultraviolet excess of the F and G type
main-sequence stars in the cluster indicate that the metallicity of the cluster
is about the solar value. We estimated the reddening $E(B-V)=0.074 \pm 0.050$
mag using the $U-B$ vs $B-V$ two-colour diagram. The distance modula, the
distance and the age of NGC 6866 were derived as $\mu = 10.60 \pm 0.10$ mag,
$d=1189 \pm 75$ pc and $t = 813 \pm 50$ Myr, respectively, by fitting
colour-magnitude diagrams of the cluster with the PARSEC isochrones. The
Galactic orbit of NGC 6866 indicates that the cluster is orbiting in a slightly
eccentric orbit with $e=0.12$. The mass function slope $x=1.35 \pm 0.08$ was
derived by using the most probable members of the cluster.
