Performance Verification of the EXtreme PREcision Spectrograph

Ryan T. Blackman*, Debra A. Fischer, Colby A. Jurgenson, David Sawyer, Tyler M. McCracken, Andrew E. Szymkowiak, Ryan R. Petersburg, J. M. Joel Ong, John M. Brewer, Lily L. Zhao, Christopher Leet, Lars A. Buchhave, René Tronsgaard, Joe Llama, Travis Sawyer, Allen B. Davis, Samuel H. C. Cabot, Michael Shao, Russell Trahan, Bijan NematiMatteo Genoni, Giorgio Pariani, Marco Riva, Paul Fournier, Rafal Pawluczyk

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The EXtreme PREcision Spectrograph (EXPRES) is a new Doppler spectrograph designed to reach a radial-velocity measurement precision sufficient to detect Earth-like exoplanets orbiting nearby, bright stars. We report on extensive laboratory testing and on-sky observations to quantitatively assess the instrumental radial-velocity measurement precision of EXPRES, with a focused discussion of individual terms in the instrument error budget. We find that EXPRES can reach a single-measurement instrument calibration precision better than 10 cm s−1, not including photon noise from stellar observations. We also report on the performance of the various environmental, mechanical, and optical subsystems of EXPRES, assessing any contributions to radial-velocity error. For atmospheric and telescope related effects, this includes the fast tip-tilt guiding system, atmospheric dispersion compensation, and the chromatic exposure meter. For instrument calibration, this includes the laser fRequency comb (LFC), flat-field light source, CCD detector, and effects in the optical fibers. Modal noise is mitigated to a negligible level via a chaotic fiber agitator, which is especially important for wavelength calibration with the LFC. Regarding detector effects, we empirically assess the impact on the radial-velocity precision due to pixel-position nonuniformities and charge transfer inefficiency (CTI). EXPRES has begun its science survey to discover exoplanets orbiting G-dwarf and K-dwarf stars, in addition to transit spectroscopy and measurements of the Rossiter–McLaughlin effect.
Original languageEnglish
Article number238
JournalAstrophysical Journal
Volume159
Issue number5
ISSN0004-637X
DOIs
Publication statusPublished - 2020

Cite this

Blackman, R. T., Fischer, D. A., Jurgenson, C. A., Sawyer, D., McCracken, T. M., Szymkowiak, A. E., Petersburg, R. R., Joel Ong, J. M., Brewer, J. M., Zhao, L. L., Leet, C., Buchhave, L. A., Tronsgaard, R., Llama, J., Sawyer, T., Davis, A. B., Cabot, S. H. C., Shao, M., Trahan, R., ... Pawluczyk, R. (2020). Performance Verification of the EXtreme PREcision Spectrograph. Astrophysical Journal, 159(5), [238 ]. https://doi.org/10.3847/1538-3881/ab811d