New Photometric Data of Old Open Clusters II. A Dataset for 36 Clusters

Abstract

We present new photometric data on 36 old open clusters using the 65-cm telescope at Gunma Astronomical Observatory. This dataset is a continuation of photometric data of old open clusters (Hasegawa et al 2004, PASJ, 56, 295) collected mainly in the antigalactic center region. By constructing a color-magnitude diagram, we inspected the main sequence and (if richly populated) red-clump stars to evaluate the cluster parameters, that is, the age, distance, and reddening, by applying an isochrone provided by the Padova group. Now, 49 old clusters have consistently measured parameters (36 clusters in this study and 13 from Hasegawa et al. 2004). The clusters are exclusively older than the Hyades cluster, and the age is distributed in the range 0.6-5.0Gyr. The oldest clusters include Auner 1, Biurakan 12, Berkeley 78, and NGC 2425. Our study includes clusters that are useful in further clarifying the outer disk of the Milky Way, and when inner clusters with galactocentric distances less than 12kpc are compared with outer ones, the latter tends to be less bound to the galactic plane. Nine clusters are found to be cospatial with the northern part of the recently identified stellar overdensity centered in the constellation of Canis Major.