Correcting HIRES radial velocities for small systematic errors

Lev Tal-Or; Trifon Trifonov; Shay Zucker; Tsevi Mazeh; Mathias Zechmeister

doi:10.1093/mnrasl/sly227

paper

Correcting HIRES radial velocities for small systematic errors

arXiv:1810.02986 · doi:10.1093/mnrasl/sly227

Abstract

The HIRES spectrograph, mounted on the $10$ -m Keck-I telescope, belongs to a small group of radial-velocity (RV) instruments that produce stellar RVs with long-term precision down to $\sim 1$ ms $^{- 1}$ . In $2017$ , the HIRES team published $64, 480$ RVs of $1, 699$ stars, collected between $1996$ and $2014$ . In this bank of RVs, we identify a sample of RV-quiet stars, whose RV scatter is $< 10$ ms $^{- 1}$ , and use them to reveal two small but significant nightly zero-point effects: a discontinuous jump, caused by major modifications of the instrument in August $2004$ , and a long-term drift. The size of the $2004$ jump is $1.5 \pm 0.1$ ms $^{- 1}$ , and the slow zero-point variations have a typical magnitude of $≲ 1$ ms $^{- 1}$ . In addition, we find a small but significant correlation between stellar RVs and the time relative to local midnight, indicative of an average intra-night drift of $0.051 \pm 0.004$ ms $^{- 1}$ hr $^{- 1}$ . We correct the $64, 480$ HIRES RVs for the systematic effects we find, and make the corrected RVs publicly available. Our findings demonstrate the importance of observing RV-quiet stars, even in the era of simultaneously-calibrated RV spectrographs. We hope that the corrected HIRES RVs will facilitate the search for new planet candidates around the observed stars.

arXiv comment5 pages, 7 figures

Correcting HIRES radial velocities for small systematic errors

Abstract

References in corpus (14)

Cited by in corpus (74)