Astrometric Calibration of the Gemini NICI Planet-Finding Campaign

Abstract

We describe the astrometric calibration of the Gemini NICI Planet-Finding Campaign. The Campaign requires a relative astrometric accuracy of $\approx$ 20 mas across multi-year timescales in order to distinguish true companions from background stars by verifying common proper motion and parallax with their parent stars. The calibration consists of a correction for instrumental optical image distortion, plus on-sky imaging of astrometric fields to determine the pixel scale and image orientation. We achieve an accuracy of $\lesssim 7$ mas between the center and edge of the 18${}^{\prime \prime }$ NICI field, meeting the 20 mas requirement. Most of the Campaign data in the Gemini Science Archive are accurate to this level but we identify a number of anomalies and present methods to correct the errors.

arXiv comment4 figures. Accepted for publication in PASP

References in corpus (10)

• Angular Differential Imaging: a Powerful High-Contrast Imaging Technique
• The Gemini NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars
• Representations of world coordinates in FITS
• The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets around Young B and A Stars
• The Gemini NICI Planet-Finding Campaign: Discovery of a Close Substellar Companion to the Young Debris Disk Star PZ Tel
• The Gemini NICI Planet-Finding Campaign : Discovery of a Substellar L Dwarf Companion to the Nearby Young M Dwarf CD-35 2722
• The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets Around Debris Disk Stars
• The Gemini NICI Planet-Finding Campaign: Discovery of a Multiple System Orbiting the Young A Star HD 1160
• The Gemini NICI Planet-Finding Campaign: The Companion Detection Pipeline
• Analysis of 70 Ophiuchi AB including seismic constraints

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• Development of the Warm Astrometric Mask for MICADO astrometry calibration
• Lessons learned from SPHERE for the astrometric strategy of the next generation of exoplanet imaging instruments