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.
Keywords
Cite
@article{arxiv.1910.08659,
title = {Revised Astrometric Calibration of the Gemini Planet Imager},
author = {Robert J. De Rosa and Meiji M. Nguyen and Jeffrey Chilcote and Bruce Macintosh and Marshall D. Perrin and Quinn Konopacky and Jason J. Wang and Gaspard Duchêne and Eric L. Nielsen and Julien Rameau and S. Mark Ammons and Vanessa P. Bailey and Travis Barman and Joanna Bulger and Tara Cotten and Rene Doyon and Thomas M. Esposito and Michael P. Fitzgerald and Katherine B. Follette and Benjamin L. Gerard and Stephen J. Goodsell and James R. Graham and Alexandra Z. Greenbaum and Pascale Hibon and Li-Wei Hung and Patrick Ingraham and Paul Kalas and James E. Larkin and Jérôme Maire and Franck Marchis and Mark S. Marley and Christian Marois and Stanimir Metchev and Maxwell A. Millar-Blanchaer and Rebecca Oppenheimer and David Palmer and Jennifer Patience and Lisa Poyneer and Laurent Pueyo and Abhijith Rajan and Fredrik T. Rantakyrö and Jean-Baptiste Ruffio and Dmitry Savransky and Adam C. Schneider and Anand Sivaramakrishnan and Inseok Song and Remi Soummer and Sandrine Thomas and J. Kent Wallace and Kimberly Ward-Duong and Sloane Wiktorowicz and Schuyler Wolff},
journal= {arXiv preprint arXiv:1910.08659},
year = {2020}
}
Comments
36 pages, 17 figures, accepted for publication in the Journal of Astronomical Telescopes, Instruments, and Systems. Updated version includes revisions made during the referee process