Near-Infrared Variability Study of the Central 2.3 arcmin x 2.3 arcmin
  of the Galactic Centre I. Catalog of Variable Sources
  We used four-year baseline HST/WFC3 IR observations of the Galactic Centre in
the F153M band (1.53 micron) to identify variable stars in the central
~2.3'x2.3' field. We classified 3845 long-term (periods from months to years)
and 76 short-term (periods of a few days or less) variables among a total
sample of 33070 stars. For 36 of the latter ones, we also derived their periods
(<3 days). Our catalog not only confirms bright long period variables and
massive eclipsing binaries identified in previous works, but also contains many
newly recognized dim variable stars. For example, we found \delta Scuti and RR
Lyrae stars towards the Galactic Centre for the first time, as well as one BL
Her star (period < 1.3 d). We cross-correlated our catalog with previous
spectroscopic studies and found that 319 variables have well-defined stellar
types, such as Wolf-Rayet, OB main sequence, supergiants and asymptotic giant
branch stars. We used colours and magnitudes to infer the probable variable
types for those stars without accurately measured periods or spectroscopic
information. We conclude that the majority of unclassified variables could
potentially be eclipsing/ellipsoidal binaries and Type II Cepheids. Our source
catalog will be valuable for future studies aimed at constraining the distance,
star formation history and massive binary fraction of the Milky Way nuclear
star cluster.
