  The open star clusters (OSC) are important tracers for understanding the
Galactic evolution. The parametric study of these astronomical-objects is
crucial task due to the appearing sequence of the members of OSC. These members
are defined through the various approaches such as photometric, statistical,
kinematics etc. In the present paper, we have been using the photometric
colours of the identified stars for categorized them into the blue and red
component groups and identification of these groups is possible through (B-V)
vs V colour magnitude diagram (CMD). Furthermore, the influence/effect of these
groups is also examined in the estimation of cluster parameters. The stellar
enhancement of cluster NGC 6866 is found through the blue-component-stars (BCS)
and the linear solution of best fitted values of King Models of the
radial-densityprofile (RDP) gives the core radius as 5.22+/-0.29 arcmin. The
good agreement of present estimated parameters of the cluster with the
literature seems to be an effective evidence to consider BCS as the true
representative of the cluster. The stellar distribution of the cluster shows
continuous phenomena of the mass segregation. An effect of the incompleteness
of photometric data is related to the mass-function slope values, which is
found to be -3.80+/-0.11 and also shows the incremental nature with the
incompleteness.
