Astrophysical and Structural Parameters, And Dynamical Evolution Of The
  Open Clusters NGC 1245 And NGC 2099
  We derive astrophysical and structural parameters of open clusters NGC 1245
and NGC 2099 from 2MASS JHKs and Gaia DR2 photometric / astrometric data bases.
Their likely members have been determined from Gaia DR2 proper motion data. Our
E(B-V) values (2MASS) are slightly smaller than the literature values, whereas
our E(B-V) values (Gaia DR2) agree with the literature within the
uncertainties. Their distance moduli/distances and ages are in good coincident
with the literature. NGC 1245 has steep negative core mass function slope (MFs)
({\chi}_core=-1.24). Its halo ({\chi}_halo=+0.78) and overall
({\chi}_overall=-0.95) MFs mean that it presents signs of small-scale mass
segregation to the outer regions from its core, due to its [{\tau}_rlx
(overall),{\tau}_overall ]=[302 Myr,5]. The MFs of NGC 2099 is very negative
steep ({\chi}_core=-2.67) in the core, and quite positive steep
({\chi}_halo=+1.41) in the halo. This kind of MF slope steeping from the core
to the outskirts indicates that low-mass stars in the core are transferred to
the cluster's outskirts, while massive stars sink in the core, because of mass
segregation. NGC 2099's flat overall MFs ({\chi}_overall=+0.91) and its
{\tau}_overall=8 presents a sign of mass segregation. These OCs with the
relatively large masses 8700 Msolar (NGC 1245) and 5660 Msolar (NGC 2099),
which locate at RGC > 9 kpc, expose to external perturbations such as tidal
effects and shock waves, and they lose their stars in low-proportions.
