  The Gemini Planet Imager (GPI) Extreme Adaptive Optics Coronograph contains
an interferometric mode: a 10-hole non-redundant mask (NRM) in its pupil wheel.
GPI operates at $Y, J, H$, and $K$ bands, using an integral field unit
spectrograph (IFS) to obtain spectral data at every image pixel. NRM on GPI is
capable of imaging with a half resolution element inner working angle at
moderate contrast, probing the region behind the coronagraphic spot. The fine
features of the NRM PSF can provide a reliable check on the plate scale, while
also acting as an attenuator for spectral standard calibrators that would
otherwise saturate the full pupil. NRM commissioning data provides details
about wavefront error in the optics as well as operations of adaptive optics
control without pointing control from the calibration system. We compare lab
and on-sky results to evaluate systematic instrument properties and examine the
stability data in consecutive exposures. We discuss early on-sky performance,
comparing images from integration and tests with the first on-sky images, and
demonstrate resolving a known binary. We discuss the status of NRM and
implications for future science with this mode.
