Revised Astrometric Calibration of the Gemini Planet Imager

Abstract

We present a revision to the astrometric calibration of the Gemini Planet Imager (GPI), an instrument designed to achieve the high contrast at small angular separations necessary to image substellar and planetary-mass companions around nearby, young stars. We identified several issues with the GPI Data Reduction Pipeline (DRP) that significantly affected the determination of angle of north in reduced GPI images. As well as introducing a small error in position angle measurements for targets observed at small zenith distances, this error led to a significant error in the previous astrometric calibration that has affected all subsequent astrometric measurements. We present a detailed description of these issues, and how they were corrected. We reduced GPI observations of calibration binaries taken periodically since the instrument was commissioned in 2014 using an updated version of the DRP. These measurements were compared to observations obtained with the NIRC2 instrument on Keck II, an instrument with an excellent astrometric calibration, allowing us to derive an updated plate scale and north offset angle for GPI. This revised astrometric calibration should be used to calibrate all measurements obtained with GPI for the purposes of precision astrometry.

arXiv comment36 pages, 17 figures, accepted for publication in the Journal of Astronomical Telescopes, Instruments, and Systems. Updated version includes revisions made during the referee process

References in corpus (13)

• Validation of the new Hipparcos reduction
• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
• Analysis of isoplanatic high resolution stellar fields by Starfinder code
• Improving Galactic Center Astrometry by Reducing the Effects of Geometric Distortion
• The Palomar/Keck Adaptive Optics Survey of Young Solar Analogs: Evidence for a Universal Companion Mass Function
• Astrometry and Photometry with Coronagraphs
• Astrometric Confirmation and Preliminary Orbital Parameters of the Young Exoplanet 51 Eridani b with the Gemini Planet Imager
• Discovery of a Substellar Companion to the Nearby Debris Disk Host HR 2562
• Gemini Planet Imager Observational Calibrations V: Astrometry and Distortion
• Hint of curvature in the orbital motion of the exoplanet 51 Eridani b using 3 years of VLT/SPHERE monitoring
• The Galactic Center: An Improved Astrometric Reference Frame for Stellar Orbits around the Supermassive Black Hole
• An updated visual orbit of the directly-imaged exoplanet 51 Eridani b and prospects for a dynamical mass measurement with Gaia
• Integral Field Spectroscopy of the Low-Mass Companion HD984B with the Gemini Planet Imager

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