  We present a new satellite in the outer halo of the Galaxy, the first Milky
Way satellite found in the stacked photometric catalog of the Panoramic Survey
Telescope and Rapid Response System 1 (Pan-STARRS1) Survey. From follow-up
photometry obtained with WFI on the MPG/ESO 2.2m telescope, we argue that the
object, located at a heliocentric distance of 145+/-17 kpc, is the most distant
Milky Way globular cluster yet known. With a total magnitude of M_V=-4.3+/-0.2
and a half-light radius of 20+/-2 pc, it shares the properties of extended
globular clusters found in the outer halo of our Galaxy and the Andromeda
galaxy. The discovery of this distant cluster shows that the full spatial
extent of the Milky Way globular cluster system has not yet been fully
explored.
