Shao-En Huang (National Central University); Wen-Ping Chen (National central University)
We are undertaking a census of star clusters toward the anti-Galactic center direction. The goal is to use a sample of known and newly found star clusters, each with well determined distance and age, to probe the surface density distribution and disk structure, particularly the spiral arm dimensions. Here we present the pilot study of Czernik 23, a relatively rich star cluster. Using Gaia/eDR3, i.e., with high-precision proper motions and parallax-determined distances, we identified a reliable list of member stars, from which a heliocentric distance of ~3.3 kpc, and an age of 180 Myr are derived. These are considerably more distant and younger, respectively, than reported in the literature. Incidentally, an uncatalogued star cluster has been found projected near Czernik 23, which we also characterized. We discuss the general statistical procedure in estimation of the distance from a parallax measurement and associated errors.