The IAG Solar Flux Atlas: Telluric Correction with a Semiempirical Model

Baker, Ashley; Blake, Cullen H.; Reiners, A.

doi:10.3847/1538-4365/ab6a1c

Cited by 10 publications

(5 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…One can see that the Levenberg-Marquardt minimization converges to residuals below the 2% P2V amplitude on the average line. The latest value is in agreement with typical telluric correction from the literature (e.g., Sameshima et al 2018;Ulmer-Moll et al 2019;Baker et al 2020). residuals in the very core of telluric lines.…”

Section: Hr 1544supporting

confidence: 90%

Automatic model-based telluric correction for the ESPRESSO data reduction software

Allart

Faria

Dumusque

et al. 2022

A&A

View full text Add to dashboard Cite

Context. Ground-based high-resolution spectrographs are key instruments for several astrophysical domains, such as exoplanet studies. Unfortunately, the observed spectra are contaminated by the Earth's atmosphere and its large molecular absorption bands. While different techniques (forward radiative transfer models, principle component analysis (PCA), or other empirical methods) exist to correct for telluric lines in exoplanet atmospheric studies, in radial velocity (RV) studies, telluric lines with an absorption depth of >2 % are generally masked, which poses a problem for faint targets and M dwarfs as most of their RV content is present where telluric contamination is important. Aims. We propose a simple telluric model to be embedded in the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) data reduction software (DRS). The goal is to provide telluric-free spectra and enable RV measurements through the cross-correlation function technique (and others), including spectral ranges where telluric lines fall. Methods. The model is a line-by-line radiative transfer code that assumes a single atmospheric layer. We use the sky conditions and the physical properties of the lines from the HITRAN database to create the telluric spectrum. This high-resolution model is then convolved with the instrumental resolution and sampled to the instrumental wavelength grid. A subset of selected telluric lines is used to robustly fit the spectrum through a Levenberg-Marquardt minimization algorithm. Results. We computed the model to the H 2 O lines in the spectral range of ESPRESSO. When applied to stellar spectra from A0-to M5-type stars, the residuals of the strongest water lines are below the 2% peak-to-valley (P2V) amplitude for all spectral types, with the exception of M dwarfs, which are within the pseudo-continuum. We then determined the RVs from the telluric-corrected ESPRESSO spectra of Tau Ceti and Proxima. We created telluric-free masks and compared the obtained RVs with the DRS RVs. In the case of Tau Ceti, we identified that micro-telluric lines introduce systematics up to an amplitude of 58 cm • s −1 and with a period of one year if not corrected. For Proxima, the impact of micro-telluric lines is negligible due to the low flux below 5900 Å. For late-type stars, the gain in spectral content at redder wavelengths is equivalent to a gain of 25% in photon noise or a factor of 1.78 in exposure time. This leads to better constraints on the semi-amplitude and eccentricity of Proxima d, which was recently proposed as a planet candidate. Finally, we applied our telluric model to the O 2 γ-band and we obtained residuals below the 2% P2V amplitude. Conclusions. We propose a simple telluric model for high-resolution spectrographs to correct individual spectra and to achieve precise RVs. The removal of micro-telluric lines, coupled with the gain in spectral range, leads to more precise RVs. Moreover, we showcase that our model can be applied to other molecules, and thus to other wavelength re...

show abstract

Section: Hr 1544supporting

confidence: 90%

Automatic model-based telluric correction for the ESPRESSO data reduction software

Allart

Faria

Dumusque

et al. 2022

A&A

View full text Add to dashboard Cite

show abstract

“…This also highlights that with current methods only limited improvement can be expected from supercalibration techniques because very few spectra are available for comparison that have a higher accuracy than provided by Espresso itself. For example, even the IAG solar flux atlas Baker et al 2020) only states a 'precision and accuracy of ±10 m/s'. However, systematics in the wavelength calibration of Fouriertransform spectrometer are likely vastly different from the ones of grating spectrographs.…”

Section: Comparison To Hires Uves and Harpsmentioning

confidence: 99%

Fundamental physics with ESPRESSO: Towards an accurate wavelength calibration for a precision test of the fine-structure constant

Schmidt

Molaro

Murphy

et al. 2021

A&A

View full text Add to dashboard Cite

Observations of metal absorption systems in the spectra of distant quasars allow one to constrain a possible variation of the fine-structure constant throughout the history of the Universe. Such a test poses utmost demands on the wavelength accuracy and previous studies were limited by systematics in the spectrograph wavelength calibration. A substantial advance in the field is therefore expected from the new ultra-stable highresolution spectrograph Espresso, which was recently installed at the VLT. In preparation of the fundamental physics related part of the Espresso GTO program, we present a thorough assessment of the Espresso wavelength accuracy and identify possible systematics at each of the different steps involved in the wavelength calibration process. Most importantly, we compare the default wavelength solution, which is based on the combination of Thorium-Argon arc lamp spectra and a Fabry-Pérot interferometer, to the fully independent calibration obtained from a laser frequency comb. We find wavelength-dependent discrepancies of up to 24 m/s. This substantially exceeds the photon noise and highlights the presence of different sources of systematics, which we characterize in detail as part of this study. Nevertheless, our study demonstrates the outstanding accuracy of Espresso with respect to previously used spectrographs and we show that constraints of a relative change of the finestructure constant at the 10 −6 level can be obtained with Espresso without being limited by wavelength calibration systematics.

show abstract

“…There are several packages that could generate synthetic telluric absorption lines to fit the observations, e.g., TAPAS (Bertaux et al 2014), Telfit (Gullikson et al 2014), MolecFit (Smette et al 2015), and other packages based on HITRAN (Rothman et al 2013;Gordon et al 2017). The best effort in modeling the observed spectra using synthetic lines are relatively successful, with a residual level of around 1%-2%, for example, in fitting a high-resolution, high-fidelity solar spectrum (Baker et al 2020). Ulmer-Moll et al (2019) compared several methods and also the most commonly used software packages to correct for telluric absorption lines using synthetic spectra, and their best results typically have residuals of around 3%-7% (1%-2% at the very best), on a similar level with that of Sameshima et al (2018).…”

Section: Introductionmentioning

confidence: 99%

“…Although there are ways to measure PWV through remote sensing data from satellites (Meier Valdés et al 2021) and using GPS (Baker et al 2017), these methods are not yet precise enough to a submillimeter level. Other challenges with modeling the absorption lines, especially the relatively deeper ones, include imperfections in the line lists and line profiles (Seifahrt et al 2010;Baker et al 2020), as well as Doppler shifts of the lines due to the wind (Figueira et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Characterizing and Mitigating the Impact of Telluric Absorption in Precise Radial Velocities

Wang

Latouf

Plavchan

et al. 2022

View full text Add to dashboard Cite

Precise radial velocity (PRV) surveys are important for the search for Earth analogs around nearby bright stars, which induce a small stellar reflex motion with an RV amplitude of ∼10 cm s−1. Detecting such a small RV signal poses challenges to instrumentation, data analysis, and the precision of astrophysical models to mitigate stellar jitter. In this work, we investigate an important component in the PRV error budget—the spectral contamination from the Earth’s atmosphere (tellurics). We characterize the effects of telluric absorption on the RV precision and quantify its contribution to the RV error budget over time and across a wavelength range of 350 nm–2.5 μm. We use simulated solar spectra with telluric contamination injected, and we extract the RVs using two commonly adopted algorithms: dividing out a telluric model before performing cross-correlation or forward modeling the observed spectrum incorporating a telluric model. We assume various degrees of cleanness in removing the tellurics. We conclude that the RV errors caused by telluric absorption can be suppressed to close to or even below 1–10 cm s−1 in the blue optical region. At red through near-infrared wavelengths, however, the residuals of tellurics can induce an RV error on the meter-per-second level even under the most favorable assumptions for telluric removal, leading to significant systematic noise in the RV time series and periodograms. If the red-optical or near-infrared becomes critical in the mitigation of stellar activity, systematic errors from tellurics can be eliminated with a space mission such as EarthFinder.

show abstract

The IAG Solar Flux Atlas: Telluric Correction with a Semiempirical Model

Cited by 10 publications

References 48 publications

Automatic model-based telluric correction for the ESPRESSO data reduction software

Automatic model-based telluric correction for the ESPRESSO data reduction software

Fundamental physics with ESPRESSO: Towards an accurate wavelength calibration for a precision test of the fine-structure constant

Characterizing and Mitigating the Impact of Telluric Absorption in Precise Radial Velocities

Contact Info

Product

Resources

About