Accounting for Chromatic Atmospheric Effects on Barycentric Corrections

Abstract

Atmospheric effects on stellar radial velocity measurements for exoplanet discovery and characterization have not yet been fully investigated for extreme precision levels. We carry out calculations to determine the wavelength dependence of barycentric corrections across optical wavelengths, due to the ubiquitous variations in air mass during observations. We demonstrate that radial velocity errors of at least several cm/s can be incurred if the wavelength dependence is not included in the photon-weighted barycentric corrections. A minimum of four wavelength channels across optical spectra (380-680 nm) are required to account for this effect at the 10 cm/s level, with polynomial fits of the barycentric corrections applied to cover all wavelengths. Additional channels may be required in poor observing conditions or to avoid strong telluric absorption features. Furthermore, consistent flux sampling on the order of seconds throughout the observation is necessary to ensure that accurate photon weights are obtained. Finally, we describe how a multiple-channel exposure meter will be implemented in the EXtreme PREcision Spectrograph (EXPRES).

arXiv comment7 pages, 5 figures, accepted for publication in ApJ

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Cited by in corpus (10)

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• Performance Verification of the EXtreme PREcision Spectrograph
• An Extreme Precision Radial Velocity Pipeline: First Radial Velocities from EXPRES
• The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities
• Wobble: A Data-driven Analysis Technique for Time-series Stellar Spectra
• EXPRES I. HD~3651 an Ideal RV Benchmark
• Photon-weighted barycentric correction and its importance for precise radial velocities
• The Measured Impact of Chromatic Atmospheric Effects on Barycentric Corrections: Results from the EXtreme PREcision Spectrograph
• Data Reduction Pipeline of the TOU Optical Very High Resolution Spectrograph and Its sub-m/s Performance
• Confirmation of Fe I on MASCARA-5 b's Dayside Observed With EXPRES