Ondřejov Echelle Spectrograph, Ground Based Support Facility for Exoplanet Missions

Abstract

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 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. ‡ This article is based on the data collected with Perek 2-m telescope. Kabath et al. 2019 2

TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration

“…We collected 32 spectra using the Ondrějov Echelle Spectrograph (OES) on the 2 m Perek telescope at the Ondrějov Observatory in the Czech Republic (Kabáth et al 2020). These observations were obtained between UT 2020 February and UT 2020 September at a cadence of 3-5 RVs per month.…”

Spectroscopy of the massive interacting binary UU Cassiopeiae

“…Finally, seventeen spectra of UU Cas together with the necessary dark frames, flat-fields, and Th-Ar comparison spectra were acquired using the Ondřejov Echelle Spectrograph (OES, resolving power 50000) attached to the Coudé focus of 2m Perek's Telescope at Ondřejov Observatory of the Astronomical Institute of Czech Academy of Sciences (cf. Koubský et al 2004;Kabáth et al 2020). These spectra were processed using a semiautomated IRAF Package prepared by M. Cabezas for this purpose, in which the standard procedures for echelle spectroscopy were used, including flat and bias correction, cosmic rays removal via a Laplacian algorithm (van Dokkum 2001), wavelength calibration using Th-Ar lamp, order merging, the rectification of spectra, and heliocentric calibration.…”

TOI-1268b: the youngest, hot, Saturn-mass transiting exoplanet

“…The instrument has a spectral resolving power of R = 50 000 (at 500 nm) and covers wavelengths from 380 nm to 900 nm. A detailed description of the instrument can be found in Kabáth et al (2020). Exposure times were set to 3600 s, resulting in S/N between 10-35 at 550 nm, depending on observing conditions and airmass.…”