Accounting for Chromatic Atmospheric Effects on Barycentric Corrections

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 t...

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Bibliographic Details
Published in:The Astrophysical journal 2017-03, Vol.837 (1), p.18
Main Authors: Blackman, Ryan T., Szymkowiak, Andrew E., Fischer, Debra A., Jurgenson, Colby A.
Format: Article
Language:English
Subjects:
ABSORPTION
ACCOUNTING
ACCURACY
Air masses
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Atmospheric correction
Atmospheric effects
Channels
COMPUTERIZED SIMULATION
CORRECTIONS
Dependence
ERRORS
Extrasolar planets
FREQUENCY DEPENDENCE
instrumentation: spectrographs
MASS
Mathematical analysis
Photometers
PHOTONS
POLYNOMIALS
RADIAL VELOCITY
SPECTRA
STARS
techniques: radial velocities
Velocity errors
WAVELENGTHS
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Summary: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−1 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−1 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).
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aa5ead