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Published December 2018 | Published + Accepted Version
Journal Article Open

Maximum Angular Separation Epochs for Exoplanet Imaging Observations


Direct imaging of exoplanets presents both significant challenges and significant gains. The advantages primarily lie in receiving emitted and, with future instruments, reflected photons at phase angles not accessible by other techniques, enabling the potential for atmospheric studies and the detection of rotation and surface features. The challenges are numerous and include coronagraph development and achieving the necessary contrast ratio. Here, we address the specific challenge of determining epochs of maximum angular separation for the star and planet. We compute orbital ephemerides for known transiting and radial velocity planets, taking Keplerian orbital elements into account. We provide analytical expressions for angular star–planet separation as a function of the true anomaly, including the locations of minimum and maximum. These expressions are used to calculate uncertainties for maximum angular separation as a function of time for the known exoplanets, and we provide strategies for improving ephemerides with application to proposed and planned imaging missions.

Additional Information

© 2018 The American Astronomical Society. Received 2018 August 28; revised 2018 October 12; accepted 2018 October 16; published 2018 November 15. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. The results reported herein benefited from collaborations and/or information exchange within NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. This work was funded by the WFIRST CGI Science Investigation Team contract #NNG16P27C (PI: Margaret Turnbull).

Attached Files

Published - Kane_2018_AJ_156_267.pdf

Accepted Version - 1810.07328.pdf


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August 19, 2023
October 19, 2023