Automated Alignment and On-Sky Performance of the Gemini Planet Imager   Coronagraph
  The Gemini Planet Imager (GPI) is a next-generation, facility instrument currently being commissioned at the Gemini South observatory. GPI combines an extreme adaptive optics system and integral field spectrograph (IFS) with an apodized-pupil Lyot coronagraph (APLC) producing an unprecedented capability for directly imaging and spectroscopically characterizing extrasolar planets. GPI's operating goal of $10^{-7}$ contrast requires very precise alignments between the various elements of the coronagraph (two pupil masks and one focal plane mask) and active control of the beam path throughout the instrument. Here, we describe the techniques used to automatically align GPI and maintain the alignment throughout the course of science observations. We discuss the particular challenges of maintaining precision alignments on a Cassegrain mounted instrument and strategies that we have developed that allow GPI to achieve high contrast even in poor seeing conditions. 
Dmitry Savransky, Sandrine J. Thomas, Lisa A. Poyneer, Jennifer Dunn,   Bruce A. Macintosh, Naru Sadakuni, Daren Dillon, Ste...
astro-ph.IM astro-ph.EP