Reanalysis of nearby open clusters using Gaia DR1/TGAS and HSOY
  Open clusters have long been used to gain insights into the structure,
composition, and evolution of the Galaxy. With the large amount of stellar data
available for many clusters in the Gaia era, new techniques must be developed
for analyzing open clusters, as visual inspection of cluster color-magnitude
diagrams is no longer feasible. An automatic tool will be required to analyze
large samples of open clusters. We seek to develop an automatic
isochrone-fitting procedure to consistently determine cluster membership and
the fundamental cluster parameters. Our cluster characterization pipeline first
determined cluster membership with precise astrometry, primarily from TGAS and
HSOY. With initial cluster members established, isochrones were fitted, using a
chi-squared minimization, to the cluster photometry in order to determine
cluster mean distances, ages, and reddening. Cluster membership was also
refined based on the stellar photometry. We used multiband photometry, which
includes ASCC-2.5 BV, 2MASS JHK_s, Gaia G band. We present parameter estimates
for all 24 clusters closer than 333 pc as determined by the Catalogue of Open
Cluster Data and the Milky Way Star Clusters catalog. We find that our
parameters are consistent to those in the Milky Way Star Clusters catalog. We
demonstrate that it is feasible to develop an automated pipeline that
determines cluster parameters and membership reliably. After additional
modifications, our pipeline will be able to use Gaia DR2 as input, leading to
better cluster memberships and more accurate cluster parameters for a much
larger number of clusters.
