5.
Conclusions
In this paper, we present CCD UBVI photometry for the two Galactic open clusters Ruprecht 25 and Czernik 6 for the first time. We have provided their fundamental parameters that are useful in statistical investigations for the open clusters in our Milky Way Galaxy. The analysis of the photometric data leads to the following main conclusions: 1. The radii are obtained as 2 .4 and 1 .5 which corresponds to 4.1 pc and 2.2 pc, respectively, at a distance of the cluster for Ruprecht 25 and Czernik 6. 2. From the two-colour (U −B ) versus (B −V ) diagram, we esti- mated the interstellar reddening as E(B −V ) = 0 . 55 ±0 . 05 mag for Ruprecht 25 and 0.48 ±0.05 for Czernik 6. 3. Distances to the cluster Ruprecht 25 and Czernik 6 are esti- mated as 5.8 ±0.5 and 5.0 ±0.3 kpc, respectively. An age of 800 ±80 Myr and 40 ±10 Myr are determined for Ruprecht 25 and Czernik 6 respectively by comparing the isochrones of Z = 0 . 019 given by Girardi et al. (20 0 0) . 4. We have found mass-segregation effect with the confidence la- bel of 90% and 85% for the clusters Ruprecht 25 and Czernik 6 respectively. Present estimate of dynamical relaxation time in- dicates that both the clusters are dynamically relaxed. This may be due to star formation process or dynamical evolution of the clusters.