Wavelength calibration and closure phases with the gemini planet imager IFS using its non-redundant mask

The Gemini Planet Imager (GPI) Extreme Adaptive Optics Coronagraph (ExAOC) possesses a non-redundant mask (NRM) mode that is enabled by placing a 10-hole mask in the plane of the apodizer. GPI uses an integral field spectrograph (IFS) operating at Y, J, H, and K. The raw IFS data images are assembled into spectral data cubes by the data pipeline according to the most recent wavelength solution. Accurate knowledge of the wavelength of each slice of data in this hyperspectral cube is essential. On GPI, NRM will be used to probe planet-forming regions and enable the discovery of young companions at separations smaller than what is achievable using the standard coronagraphic mode. We show that NRM data can also provide a reliable independent and precise check on the assumed wavelength calibration of the cubes. This data also provides a reliable measure of pupil geometry, which can feed advanced coronagraphic data analysis techniques. We present a wavelength calibration procedure using images from GPI during its integration and tests. We demonstrate improvements of the instrument and data pipeline between September 2012 and July 2013, comparing integration and test data taken in each of these dates. We additionally report on the first measured closure phases calculated with GPI's NRM using two different methods, a Fourier-plane approach and an image-plane approach. The performance of NRM during integration and test is indicative of the contrast it will achieve on sky.