A catalog of newly identified star clusters in GAIA DR2
  We present the Star cluster Hunting Pipeline (SHiP) which can identify star
clusters in GAIA DR2 data, and establish a star cluster catalog for the
Galactic disk. A Friend of Friend based cluster finder method is used to
identify star clusters using 5-dimensional stellar parameters, $l, b, \varpi,
\mu_\alpha\cos\delta$, and $\mu_\delta$. Our new catalog contains 2443 star
cluster candidates identified from disk stars located within $|b|=25^\circ$ and
with $G<18$ mag. An automatic isochrone fitting scheme is applied to all
cluster candidates. With a combination of parameters obtained from isochrone
fitting, we classify cluster candidates into three classes (Class 1, 2 and 3).
Class 1 clusters are the most probable star cluster candidates with the most
stringent criteria. Most of these clusters are nearby (within 4 kpc). Our
catalog is cross-matched with three Galactic star cluster catalogs, Kharchenko
et al. (2013), Cantat-Gaudin et al. (2018, 2019), and Bica et al. (2019). The
proper motion and parallax of matched star clusters are in good agreement with
these earlier catalogs. We discover 76 new star cluster candidates that are not
listed in these 3 catalogs. The majority of these are clusters older than
log(age/yr)=8.0, and are located in the inner disk with $|b|<5^\circ$. The
recent discovery of new star clusters suggests that current Galactic star
cluster catalogs are still incomplete. Among the Class 1 cluster candidates, we
find 56 candidates for star cluster groups. The pipeline, the catalog and the
member list containing all candidates star clusters and star cluster groups
have been made publicly available.
