24 July 2014 Gemini planet imager observational calibrations VIII: characterization and role of satellite spots
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The Gemini Planet Imager (GPI) combines extreme adaptive optics, an integral field spectrograph, and a high performance coronagraph to directly image extrasolar planets in the near-infrared. Because the coronagraph blocks most of the light from the star, it prevents the properties of the host star from being measured directly. Instead, satellite spots, which are created by diffraction from a square grid in the pupil plane, can be used to locate the star and extract its spectrum. We describe the techniques implemented into the GPI Data Reduction Pipeline to measure the properties of the satellite spots and discuss the precision of the reconstructed astrometry and spectrophotometry of the occulted star. We find the astrometric precision of the satellite spots in an H-band datacube to be 0.05 pixels and is best when individual satellite spots have a signal to noise ratio (SNR) of > 20. In regards to satellite spot spectrophotometry, we find that the total flux from the satellite spots is stable to ~7% and scales linearly with central star brightness and that the shape of the satellite spot spectrum varies on the 2% level.
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Jason J. Wang, Jason J. Wang, Abhijith Rajan, Abhijith Rajan, James R. Graham, James R. Graham, Dmitry Savransky, Dmitry Savransky, Patrick J. Ingraham, Patrick J. Ingraham, Kimberly Ward-Duong, Kimberly Ward-Duong, Jennifer Patience, Jennifer Patience, Robert J. De Rosa, Robert J. De Rosa, Joanna Bulger, Joanna Bulger, Anand Sivaramakrishnan, Anand Sivaramakrishnan, Marshall D. Perrin, Marshall D. Perrin, Sandrine J. Thomas, Sandrine J. Thomas, Naru Sadakuni, Naru Sadakuni, Alexandra Z. Greenbaum, Alexandra Z. Greenbaum, Laurent Pueyo, Laurent Pueyo, Christian Marois, Christian Marois, Ben R. Oppenheimer, Ben R. Oppenheimer, Paul Kalas, Paul Kalas, Andrew Cardwell, Andrew Cardwell, Stephen Goodsell, Stephen Goodsell, Pascale Hibon, Pascale Hibon, Fredrik T Rantakyrö, Fredrik T Rantakyrö, } "Gemini planet imager observational calibrations VIII: characterization and role of satellite spots", Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 914755 (24 July 2014); doi: 10.1117/12.2055753; https://doi.org/10.1117/12.2055753

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