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arXiv · 1411.0641

Astrometric Calibration of the Gemini NICI Planet-Finding Campaign

Thomas L. Hayward·Beth A. Biller·Michael C. Liu·Eric L. Nielsen·Zahed Wahhaj·Mark Chun·Christ Ftaclas·Markus Hartung·Douglas W. Toomey
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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$''$ 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.

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Thomas L. Hayward, Beth A. Biller, Michael C. Liu, Eric L. Nielsen, Zahed Wahhaj, Mark Chun, Christ Ftaclas, Markus Hartung, Douglas W. Toomey. 2014-11-03. Astrometric Calibration of the Gemini NICI Planet-Finding Campaign. https://doi.org/10.1086/679508

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