Photometric studies of open star clusters Haffner 11 and Czernik 31
  We present the broad band UBVI CCD photometric investigations in the region
of the two open clusters Haffner 11 and Czernik 31. The radii of the clusters
are determined as 3.5 arcmin and 3.0 arcmin for Haffner 11 and Czernik 31
respectively. Using two colour (U-B) versus (B-V) diagram we determine the
reddening E(B-V) = 0.50+/-0.05 mag and 0.48+/-0.05 mag for the cluster Haffner
11 and Czernik 31 respectively. Using 2MASS JHKs and optical data, we
determined E(J-K) = 0.27+/-0.06 mag and E(V-K) = 1.37+/-0.06 for Haffner 11 and
E(J-K) = 0.26+/-0.08 mag and E(V-K) = 1.32+/-0.08 mag for Czernik 31. Our
analysis indicate normal interstellar extinction law in the direction of both
the clusters. Distance of the clusters is determined as 5.8+/-0.5 Kpc for
Haffner 11 and 3.2+/-0.3 Kpc for Czernik 31 by comparing the ZAMS with the CM
diagram of the clusters. The age of the cluster has been estimated as 800+/-100
Myr for Haffner 11 and 160+/-40 Myr for Czernik 31 using the stellar isochrones
of metallicity Z = 0.019.
