Ondřejov Echelle Spectrograph, Ground Based Support Facility for Exoplanet Missions

Fulfilling the goals of space-based exoplanetary transit surveys, like Kepler and TESS, is impossible without ground-based spectroscopic follow-up. In particular, the first-step vetting of candidates could easily necessitate several hundreds of hours of telescope time - an area where 2 m class telescopes can play a crucial role. Here, we describe the results from the science verification of the Ondřejov Echelle Spectrograph (OES) installed on the 2 m Perek telescope. We discuss the performance of the instrument as well as its suitability for the study of exoplanetary candidates from space-based transit surveys. In spite of being located at an average European observing site, and originally being conceived for the study of variable stars, OES can prove to be an important instrument for the exoplanetary community in the TESS and PLATO era - reaching accuracies of a few tens of m s^-1 with reasonable sampling and signal-to-noise for sources down to V ∼ 13. The stability of OES is demonstrated via long-term monitoring of the standard star HD 109358, while its validity for exoplanetary candidate verification is shown using three K2 candidates EPIC 210925707, EPIC 206135267 and EPIC 211993818, to reveal that they are false positive detections.