128 Microlensing Events from the Three Years of Zwicky Transient
  Facility Phase One
  Microlensing events have historically been discovered throughout the Galactic
bulge and plane by surveys designed solely for that purpose. We conduct the
first multi-year search for microlensing events on the Zwicky Transient
Facility (ZTF), an all-sky optical synoptic survey that observes the entire
visible Northern sky every few nights. We discover 128 high quality
microlensing events in the three years of ZTF-I using the bulk lightcurves in
the ZTF Public Data Release 5. We find an excess of long-duration Galactic
plane events when comparing our results to both previous surveys and
simulations. 35 of our events are found outside of the Galactic plane ($|b|
\geq 15^\circ$), nearly tripling the number of previously discovered events in
the stellar halo from surveys pointed toward the Magellanic Clouds and the
Andromeda Galaxy. We also record 1690 ongoing candidate events as potential
microlensing that can continue to be observed by ZTF-II for identification. The
scalable and computationally efficient methods developed in this work can be
applied to future synoptic surveys such as the Rubin Observatory's Legacy
Survey of Space and Time and the Nancy Grace Roman Space Telescope as they
attempt to find microlensing events in even larger and deeper datasets.
