Extreme Precision in Radial Velocity IV

Sunstar Hotel, Grindelwald, Switzerland

Sunstar Hotel, Grindelwald, Switzerland

Dorfstrasse 168, 3818 Grindelwald Switzerland
Xavier Dumusque (University of Geneva)

Following the tradition of previous workshops organised in Penn State and Yale, this fourth opus will dig into the instrumental and data analysis challenges required to enable the detection of an Earth twin using Doppler velocimetry.

As we know, today's main limitations are the instrumental precision and stellar activity that perturb radial-velocity measurements. This edition of the workshop will therefore focus on:

  • lessons learned from past and next generation EPRV instruments,
  • hardware challenges,
  • modelling and diagnosing stellar noise,
  • mitigating stellar and instrumental noises.

Confirmed speakers:

Stellar signals

- Nadège Meunier (Stellar signals)


- Jessi Cisewski (Statistical techniques to unveil planetary signals)


- James Beletic (
President, Teledyne Imaging Sensors, Detectors for EPRV)
- Suvrath Mahadevan (
Building an efficient spectrograph)
- Samuel Halverson (RV error budget)
- Arpita Roy (RV pipelines)

NIR Spectrographs

- Ilaira Carleo (The GIANO spectrograph)
- Jonathan Crass (The iLocator spectrograph)
- François Bouchy (The NIRPS and SPIROU spectrograph)
- Joe Ninan (The HPF spectrograph)
- Ignasi Ribas (The CARMENES spectrograph)
- Motohide Tamura (The IRD spectrograph)

VIS Spectrographs

- Francesco Pepe (The ESPRESSO spectrograph)
- Paul Robertson (The NEID spectrograph)
- Christian Schwab (TBC, The VELOCE spectrograph)
- Samantha Thompson (The HARPS 3 spectrograph)
- Rob Wittenmyer (The MINERVA + SONG spectrographs)
- Lily Zaho (The EXPRES spectrograph)

Workshop SOC:

Suzanne Aigrain, Fabienne Bastien, Isabelle Boisse, Aldo Bonomo, Heather Cegla, Jessi Cisewski, Xavier Dumusque (Chair), Michael Endl, Debra Fischer, Dawn Gelino, Andrew Howard, Dave Latham, Christophe Lovis, Suvrath Mahadevan, Francesco Pepe, Ansgar Reiners, Stephane Udry, Jason Wright, Sharon Xuesong Wang

Workshop LOC:

Heather Cegla, Michael Cretignier, Xavier Dumusque, Nathan Hara, Louise Nielsen, Alejandro Suarez Mascareno, Gael Ottoni, Emilie Rickman, Chantal Tacoy



  • Aida Behmard
  • Aldo Stefano Bonomo
  • Alessandro Sozzetti
  • Alexandra COATES
  • Andreas Quirrenbach
  • Andreea Ioana Gornea
  • Andrew Howard
  • Andrew Szentgyorgyi
  • Anne Boucher
  • Annelies Mortier
  • Ansgar Reiners
  • Arpita Roy
  • Baptiste Lavie
  • BJ Fulton
  • Blaise Kuo Tiong
  • Bradford Holden
  • Bruno Chazelas
  • Chad Bender
  • Charles Beichman
  • Chris Tinney
  • Christian Schwab
  • Christoph Bergmann
  • Christophe Lovis
  • Cullen Blake
  • Damien Segransan
  • David Ciardi
  • David Coutts
  • David Latham
  • David Montes
  • Dawn Gelino
  • Debra Fischer
  • Dinko Milakovic
  • Domenico Barbato
  • Don Pollacco
  • Duncan Wright
  • Elisabeth Newton
  • Emily Martin
  • Eric Mamajek
  • Erik Petigura
  • Evangelos Nagel
  • Ewelina Obrzud
  • Francesco Pepe
  • Francois Bouchy
  • Francois Wildi
  • Fred Hearty
  • Gael Ottoni
  • Gert Raskin
  • Gudmundur Stefansson
  • Heather Cegla
  • Howard Isaacson
  • Ignasi Ribas
  • Ilaria Carleo
  • Ines Juvan-Beaulieu
  • Isabelle Boisse
  • Jacob Luhn
  • James Beletic
  • Jason Wright
  • Jean Baptiste Delisle
  • Jeff Crane
  • Jennifer Burt
  • Jinglin Zhao
  • Joe Ninan
  • Johanna Teske
  • Jonathan Crass
  • João Camacho
  • João Faria
  • Julian Stuermer
  • Klaus G. Strassmeier
  • Kyle Kaplan
  • Lars A. Buchhave
  • Lee Rosenthal
  • Lily Zhao
  • Lisa Crause
  • Louise Dyregaard Nielsen
  • Mario Damasso
  • Mathias Zechmeister
  • Matteo Pinamonti
  • Maxime Marmier
  • Melissa Hobson
  • Michael Cretignier
  • Molly Kosiarek
  • Nadege Meunier
  • Natasha Latouf
  • Nathan Hara
  • Nicolas Blind
  • Nuno Santos
  • Paolo Giacobbe
  • Patrick Newman
  • Paul Robertson
  • Pedro Viana
  • Peter Plavchan
  • Priyanka Chaturvedi
  • Raphaëlle Haywood
  • Rob Wittenmyer
  • Ryan Cloutier
  • Saeed Hojjatpanah
  • Sagi Ben-Ami
  • Sam Halverson
  • Samantha Thompson
  • Scott Diddams
  • Sepideh Sadegi
  • Sharon Xuesong Wang
  • Shay Zucker
  • Shubham Kanodia
  • Silvia Sabotta
  • Solène Ulmer-Moll
  • Sophia Sulis
  • Stephane Udry
  • Steve Gibson
  • Sudeshna Boro Saikia
  • Suvrath Mahadevan
  • Takayuki Kotani
  • Tilo Steinmetz
  • Tobias Feger
  • Tobias Herr
  • Victor Brasch
  • Vinesh Maguire-Rajpaul
  • Warrick Ball
  • William Matzko
  • Xavier Dumusque
  • Yujuan Liu
    • 5:00 PM 6:30 PM
      Registration (next to hotel registration desk) 1h 30m
    • 6:30 PM 7:30 PM
      Welcome drink (hotel lobby) 1h
    • 9:00 AM 10:30 AM
      Stellar signals 1: (Chair: Heather Cegla)
      • 9:00 AM
        Mitigating stellar signals to reveal other Earths: review on the impact of stellar activity on exoplanet detectability 30m

        The first part of this review will be devoted to the different stellar processes leading to spurious radial velocities. They are due to magnetic activity (spots, plages, and flares to a lesser extent) and to flows at various scales (from granulation to meridional circulation), or a combination of both (inhibition of the convective blueshift in plages). The second part of the talk will review approaches which have been followed by various groups over the past years to characterize these effects and then to mitigate them to be able to reach small mass planet.

        Speaker: Dr Nadège Meunier (University of Grenoble)
      • 9:30 AM
        Studying Radial-velocity variations of active stars in the CARMENES Survey for Exoplanets 20m

        Understanding the effect of stellar activity on the measured radial velocity (RV) is essential for the reliable detection of exoplanets around stars. It becomes even more vital when we are searching for low-mass planets around M-dwarfs, which are known to be particularly affected by active regions. Photospheric activity features in M-dwarfs stem from the depth of the convective layers and manifest themselves on the stellar disc as cool spots and hot faculae. The shape of the spectral line profiles gets distorted due to the temperature contrast between the photosphere and active regions depending on the sensitivity of the lines to temperature. Finding and treating activity-sensitive spectral lines in M-dwarfs is not trivial since atomic lines are heavily blended between themselves and with molecular bands. However, since the temperature contrast is wavelength dependent the distortion of line profiles tends to be more pronounced at shorter wavelengths and diminishes toward longer ones. Therefore, the amplitude of spot/faculae-induced RV variations is larger in the blue region of the spectrum compared to the red one (chromaticity). The CARMENES spectrograph covers a wide spectral range of 0.52 to 0.96 µm for the visible and 0.96 to 1.71 µm for the near-infrared and is ideal for studying the difference in the amplitude of the RV jitters.
        In the CARMENES survey, we observed about 340 nearby M-dwarfs from January 2016 to November 2018. A sample of 53 highly active stars is selected that show significant RV excursion due to activity. However, only half of these targets show chromaticity in their radial velocities. We studied different parameters of the chromatic stars such as spectral type, vsini, inclination of the rotation axis, chromospheric activity indicators (e.g. the H-alpha and CaII IRT line strengths), and parameters characterizing the average absorption line shape (aka “dLW” and “CCF parameters”) and compare them to the remaining known active stars in the CARMENES sample which do not show chromatic behavior. We wish to understand why not all active stars show chromaticity and determine in which parameters those that show it and those that do not differ.

        Speaker: Ms Sepideh Sadegi (Landessternwarte/MPIA Heidelberg)
      • 9:50 AM
        HARPS-N radial velocities from the Sun-as-a-star 20m

        Distinguishing between a signal induced by stellar activity or a planet is the main challenge in radial velocity (RV) searches for low-mass exoplanets these days. Even when the presence of a transiting planet and hence its period are known, stellar activity is often the main barrier in nailing down the correct amplitude of the planetary signal. Observing the Sun-as-a-star provides a unique test case to probe activity-related signals in RV data. I will present the first results of three years of HARPS-N data of the Sun-as-a-star.
        In this talk, I will take you through the different steps of automatic data processing needed to be able to treat the Sun as a star. I will show the significant signals we find from granulation on a daily basis and solar activity on longer timescales. By using stacked periodograms, the highly variable nature of the solar RV data can be be presented. I will show you how line-shape variability clearly correlates with the RVs, but with a time delay.

        Speaker: Annelies Mortier (University of Cambridge)
      • 10:10 AM
        Line by line radial velocities to mitigate stellar activity 20m
        Speaker: Xavier Dumusque (Université de Genève)
    • 10:30 AM 11:00 AM
      Coffee break 30m
    • 11:00 AM 12:30 PM
      Stellar signal 2: (Chair: Debra Fischer)
      • 11:00 AM
        Extremely Precise Radial Velocities: From Periodic Signals to Planet Detections 20m

        It is quite common to find periodic signals in time series of precise radial velocities that cannot unambiguously be attributed either to a planetary companion or to intrinsic variability of the star. In such cases, plausibility criteria (e.g., fit quality, expected “typical” RV jitter, dynamical stability) and different types of additional information (e.g., stability of line profiles or line bisectors, color dependence of RVs, activity indicators, photometry) have been used to decide between the two possibilities; sometimes a clear conclusion is just not possible.
        I will present methods intended to separate planet detections from RV “noise” with emphasis on K giants and M dwarfs, and discuss the results.
        K giants are particularly difficult in this respect, as they display relatively large intrinsic RV variations, which are only partially understood, and depend strongly on the specific parameters (temperature, gravity, evolutionary state) of each individual star. A survey of the literature shows rather large differences in the ways that intrinsic RV variability has been taken into account, and consequently in the reliability of published planets orbiting giant stars. I will report on progress towards compiling a consolidated sample of these planets.
        The CARMENES instrument has been optimized and built specifically for an RV survey of M dwarfs. It covers multiple activity indicators and a wide wavelength range; the data reduction pipeline produces several diagnostics on line indices, line shapes, and color dependence of the RV by default. I will discuss how these are taken into account in the scientific exploitation of the CARMENES survey, in order to characterize M dwarf activity, and to establish low-mass planetary companions with high confidence.
        I will conclude with some general “lessons learned” from these projects, regarding best practices in publishing planet detections in RV data, and the design of spectrographs and survey strategies that facilitate planet detections in the presence of stellar RV variability.

        Speaker: Prof. Andreas Quirrenbach (Landessternwarte, ZAH, U Heidelberg)
      • 11:20 AM
        Reconciling the planetary interpretation of the radial velocity super-Earth K2-18c 20m

        The nearby mid-M dwarf K2-18 hosts a known transiting super-Earth. The so-called K2-18b orbits close to the inner edge of the habitable zone making it an interesting target for future atmospheric characterization of an M dwarf planet receiving Earth-like insolation. In 2017, the HARPS follow-up campaign to characterize the mass of K2-18b revealed a strong periodic signal at $\sim 9$ days that was shown to likely be due to a second, non-transiting super-Earth (K2-18c) located interior to orbit of K2-18b. However, independent CARMENES observations of this system in 2018 revealed a significantly weaker 9-day signal and claimed that its origin is more likely related to stellar activity because of the signal strength's apparent chromatic and temporal variability. I will present results from the continued HARPS monitoring of K2-18 and our self-consistent modelling efforts of the joint HARPS plus CARMENES data aimed at reconciling the nature of the 9-day signal. We conclude that the chromatic and temporal variations in the periodic signal strength is consistent with a planetary signal modulated by changing levels of stellar activity. We also conclude that the disparate results from HARPS and CARMENES are likely due to sub-optimal time-sampling in the CARMENES window function which appears to artificially suppress the K2-18c periodicity. This work highlights the importance of understanding one's time-sampling and the importance of probabilistic modelling of planets and stochastic activity, particularly when searching for sub-Neptune-sized planets with radial velocities.

        Speaker: Mr Ryan Cloutier
      • 11:40 AM
        FIESTA: new technique to parametrize stellar variability 20m

        We've been developping a new technique - FourIEr $\textit{phase}$ SpecTrum Analysis ($\mathit{\Phi}$ESTA or FIESTA) - that studies the spectral line profile variability in the Fourier space. It enables us to distinguish a line deformation from a line shift and provides the possibility to correct jitter. I will briefly lay out the theories and demonstrate its application in two example stars: (1) HD189733: Rossiter–McLaughlin effect as jitter; (2) $\alpha$ Centauri B.

        Speaker: Jinglin Zhao (UNSW)
      • 12:00 PM
        Discussion: Stellar activity 30m
    • 12:30 PM 2:00 PM
      Lunch 1h 30m
    • 2:00 PM 3:45 PM
      Splinter EPRV in NIR: (Organiser: Joe Ninan)
    • 2:00 PM 3:45 PM
      Splinter From raw spectra to EPRV:RV pipeline: (Organiser: Arpita Roy)
    • 2:00 PM 3:45 PM
      Splinter Stellar signals: oscillations and granulation: (Organisers: Heather Cegla, Raphaëlle Haywood)
    • 3:45 PM 4:30 PM
      Coffee break 45m
    • 4:30 PM 6:00 PM
      Telluric contamination in EPRV: (Chair: Sharon X. Wang)
      • 4:30 PM
        Review: Telluric contamination 30m
        Speaker: Prof. Cullen Blake (University of Pennsylvania)
      • 5:00 PM
        Is telluric correction required for precise radial velocities? 20m

        Stellar spectra are polluted with the absorption lines produced by the Earth's atmosphere. Earlier modeling work showed that a perfect telluric correction increases the radial velocity precision compared to masking the regions affected by telluric absorption. But what is the case for real observations? With CARMENES near-infrared spectra, I will show the impact of the telluric correction on the radial velocity precision effectively derived, before and after telluric correction using the synthetic transmission method Molecfit. I will discuss the advantages and limitations of the synthetic transmission methods. Finally, with ESPRESSO data, I will show the impact of the correction methods on the micro-telluric lines (< 2%) and their possible improvements.

        Speaker: Dr Solene Ulmer-Moll (IA/U. Porto)
      • 5:20 PM
        Effects of Tellurics in PRVs and Effectiveness of Mitigation Strategies 20m

        We performed simulations using the Kurucz solar spectrum and TAPAS generated telluric spectra across a year with varying atmospheric conditions to quantify the effects of telluric contamination in PRVs. We chose the wavelength range from 350nm to 2.5 micron and assumed a spectral resolution of R=120,000 with no photon noise. We assumed perfectly known spectral PSF, wavelength solution, and stellar mask/template to isolate the effects of tellurics. We will illustrate the added RV error due to tellurics as a function of wavelength and telluric content. We compared two mitigation methods: dividing out the telluric spectrum then CCF, vs. forward modeling. For the forward modeling approach, we assessed the impact of imperfect knowledge of the atmospheric line profile by fitting the simulated observed spectra using an input telluric spectrum with wrong line profiles. We conclude that forward modeling is a more effective method in mitigating tellurics. This study is part of a NASA mission concept study, EarthFinder.

        Speaker: Ms Natasha Latouf (George Mason University)
      • 5:40 PM
        Telluric emission and absorption correction in the HPF and NEID pipeline 20m

        Emission and absorption from the Earth’s atmosphere at infrared and optical wavelengths introduces a significant source of contamination for ground based precision RV spectroscopy. These telluric features not only add statistical noise and remove flux from our spectra, but introduce additional uncertainty because some of the telluric line strengths themselves are highly variable and not known a priori. I will present our latest methods for fitting and removing telluric emission and absorption in the HPF and NEID pipelines, and the potential of using these data for ancillary atmospheric science. We observe telluric emission simultaneously with the science data through a sky fiber that is offset from the science target. Telluric absorption is observed in the spectrum of the science target itself. We use laser frequency comb emission lines to measure our instrumental PSF at closely spaced regular intervals. To calculate the telluric emission line strengths, we simulate the level populations of the rovibrationally excited molecules (e.g. OH and O2) that give rise to the emission lines. To calculate the telluric absorption line strengths, we use atmospheric radiative transfer models to calculate the column densities of the absorbing species. Using the measured instrumental PSF and simulated line strengths, we then forward model the telluric emission and absorption lines and iteratively fit the forward model to the science data varying the molecular level populations until the best fit is found. These model fits not only provide a noise free way to correct for telluric emission and absorption, but also provide a long baseline of continuous observations for ancillary atmospheric science.

        Speaker: Kyle Kaplan (The University of Arizona)
    • 7:00 PM 11:00 PM
      Social event 4h

      Apero at Chuglä Bar (Nordwandplatz)
      Fondue at Barry's restaurant (Hotel Eiger)

    • 9:00 AM 10:30 AM
      Instrument and calibration challenges: (Chair: Suvrath Mahadevan)
      • 9:00 AM
        Review: Error budge in EPRV 30m
        Speaker: Dr Sam Halverson (MIT)
      • 9:30 AM
        High Performance Infrared Detectors for EPRV Measurements 30m
        Speaker: Dr Jim Beletic (Teledyne Imaging Sensors)
      • 10:00 AM
        Electro-optic laser frequency comb for spectrograph calibration 15m

        Laser frequency combs (LFCs) comprising thousands of evenly spaced laser lines with absolutely and precisely known optical frequencies can meet the calibration requirements for extreme precision in radial velocity measurements.

        We present a LFC for accurate and precise spectrograph calibration in the near-infrared. The LFC is based on electro-optic modulation of a continuous-wave laser and provides comb lines readily resolvable by an astronomical spectrograph without the need for spectral filtering. After temporal compression and spectral broadening, the system currently provides more than 5’000 comb lines spaced by 14.5 GHz covering the wavelength range from 1280 nm to 1880 nm. The spectral coverage and the LFC’s line spacing can be modified to accommodate the specific needs of the spectrograph. Owing to its all-fibre design, the system is alignment-free and of low operational complexity. As all critical components rely on mature optical telecommunication technology, the system is inherently robust and suitable for long-term and low-maintenance operation. Successful performance test of the LFC was performed on the GIANO-B spectrograph demonstrating a photon-noise-limited spectrograph calibration precision of <10 cm/s and an on-sky performance only limited by telluric interference. Current efforts are concentrated on extending the spectral span, which will lead to increased radial velocity calibration precision.

        Speaker: Mrs Ewelina Obrzud (Department of Astronomy, University of Geneva)
      • 10:15 AM
        Rubidium traced Etalon wavelength calibrators: towards deployment at observatories 15m

        Precise wavelength calibration is a persistent problem for highest precision Doppler spectroscopy. The ideal calibrator provides an extremely stable spectrum of equidistant, narrow lines over a wide bandwidth, is reliable over timescales of years, and simple to operate. Unlike traditional hollow cathode lamps, etalons provide an engineered spectrum with adjustable line distance and width, and can cover a very broad spectral bandwidth. We have shown that laser locked etalons provide the necessary stability with an ideal spectral format for calibrating precision Echelle spectrographs, in a cost-effective and robust package. Anchoring the Etalon spectrum to a very precisely known hyperfine transition of Rubidium delivers cm/s-level stability over timescales of years. We have engineered a fieldable system which is currently being constructed as calibrator for the Maroon-X, Hermes, KPF, FIES and iLocater spectrographs.

        Speaker: Prof. Christian Schwab (Macquarie University)
    • 10:30 AM 11:00 AM
      Coffee break 30m
    • 11:00 AM 12:30 PM
      Computational and statistical challenges: (Chair: Aldo Bonomo)
      • 11:00 AM
        Review: Statistical Methods for Estimating Radial Velocities in the Presence of Stellar Activity 30m

        Estimating precise radial velocities due to orbiting exoplanets in the presence of stellar activity is a challenging statistical problem. As instrumentation continues to improve, allowing for the detection of sub meter-per-second shifts, the effect of stellar activity becomes more problematic because the stellar activity can cause distortions in the spectra that mimic the RV of an orbiting exoplanet potentially leading to false detections. In this review, I will discuss various statistical methods that have been developed to address this issue, and suggest some additional routes forward.

        Speaker: Dr João Faria (Institute of Astrophysics and Space Sciences, University of Porto)
      • 11:30 AM
        Gaussian processes regression networks for the analysis of RV data 20m

        Since the discovery of the first extra-solar planet in 1995, Doppler spectroscopy proved to be one of the most successful methods in the search of exoplanets. With new high precision instruments like ESPRESSO and new data analysis methods, it will be possible to detect Earth-like planets on Sun-like stars with similar orbital parameters of Earth. Unfortunately, the search for exoplanets comes with several challenges. Stellar noise usually contaminates the RV measurements, due to the intrinsic activity star, that can hide or mimic planetary signals. Besides this problem, it is also difficult to ascertain the real number of planetary signals present in the data.
        To deal with these two issues it was developed a tool called kima. This freely available software combines an MCMC algorithm known as diffusive nested sampling with Gaussian processes (GP) to model the stellar component of the signal and infer the number and properties of the existing planetary signals.
        A new version of kima is being developed combining the previous MCMC algorithm with a Gaussian processes regression network (GPRN) that combines the properties of a Bayesian neural network with the flexibility of the GPs. The novelty of this regression network comes with its ability to take into account multiple inputs such as RV, bisector inverse slope, full width half maximum and activity indicators, e.g. log(R_hk).
        This GPRN will be an adaptive mixture of GPs that accommodates the signal and noise correlations from various output variables. It will allow the full characterization of the stellar activity in a set of RV measurements and disentangle planetary signals, stellar activity, telluric contamination, and instrumental noise from the stellar spectra, bringing us ever closer to the
        detection of Earth-like planets in the habitable zone of Sun-like stars.

        Speaker: João Camacho (Instituto de Astrofísica e Ciências do Espaço)
      • 11:50 AM
        Robustness of eccentricity estimates 20m

        The eccentricity of a planet is a key information on its present dynamics and puts constraints on formation scenarios. However, eccentricity estimates are known to be subject to caution, for instance it has been shown that low eccentricities are on average overestimated. In this talk, we present a comprehensive study of the eccentricity estimation from radial velocity data and give conditions for robust inference. We address in particular whether the estimates can be trusted even if the model used for the data analysis is incorrect. By that we mean that the data contains unmodelled stellar noises, missed planetary companion, poorly chosen priors... We present which types of modelling errors affect most the eccentricity estimates, and also discuss the numerical errors effects. We suggest data analysis methods to determine if the eccentricity of a planet is to be trusted or if it is an artefact of an inappropriate modelling.

        Speaker: Mr Nathan Hara (Université de Genève)
      • 12:10 PM
        Data-Driven Spectroscopy of Cool Stars at High Spectral Resolution 20m

        The advent of large-scale spectroscopic surveys underscores the need to develop robust techniques for determining stellar properties (“labels”, i.e., physical parameters and elemental abundances). However, traditional spectroscopic methods that utilize stellar models struggle to reproduce cool (<4700 K) stellar atmospheres due to an abundance of unconstrained molecular transitions, making modeling via synthetic spectral libraries difficult. Because small, cool stars such as K and M dwarfs are both common and good targets for finding small, cool planets, establishing precise spectral modeling techniques for these stars is of high priority. To address this, we apply The Cannon, a data-driven method of determining stellar labels, to Keck High Resolution Echelle Spectrometer (HIRES) spectra of 141 cool (<5200 K) stars from the California Planet Search. Our implementation is capable of predicting labels for small (<1 R⊙) stars of spectral types K and later with accuracies of 68 K in effective temperature (Teff), 5% in stellar radius (R∗), and 0.08 dex in bulk metallicity ([Fe/H]), and maintains this performance at low spectral resolutions (R < 5000). As M-dwarfs are the focus of many future planet-detection surveys, this work can aid efforts to better characterize the cool star population and uncover correlations between cool star abundances and planet occurrence for constraining planet formation theories.

        Speaker: Aida Behmard (Caltech)
    • 12:30 PM 2:00 PM
      Lunch 1h 30m
    • 2:00 PM 3:45 PM
      Splinter Stellar signals and statistics: (Organisers: Heather Cegla, Raphaël Haywood, Nathan Hara, Sophia Sulis)
    • 2:00 PM 3:45 PM
      Splinter Telluric contamination in EPRV: (Organiser: Evangelos Nagel)
    • 3:45 PM 4:30 PM
      Coffee break 45m
    • 4:30 PM 6:05 PM
      Optical challenges: (Chair: Francesco Pepe)
      • 4:30 PM
        Review: Spectrograph design for EPRV 30m
        Speaker: Prof. Mahadevan Suvrath (Penn State Unibversity)
      • 5:00 PM
        Review: Light injection into EPRV spectrographs 30m
        Speaker: Dr Bruno Chazelas (University of Geneva)
      • 5:30 PM
        FIOS: A Fabry Perot Instrument for O2 Searches 15m

        With new missions and surveys such as TESS and SPECULOUS, the discovery of the first transiting, potentially earth-like planets is just around the corner. Once discovered, those planets will immediately become the focus of observations in search of atmospheric biomarkers such as H2O, CH4, O3, and O2. Recent studies suggest the latter will be best detected from the ground. Here we present a study of technical and observational parameters which will produce the most sensitive observations of O2 using instrumentation on the next generation of extremely large telescopes (ELTs). Our study suggests spectral resolution in excess of R~100,000 is optimal for O2 detection. Therefore, we have developed a concept instrument based on an array of Fabry Perot Interferometers capable of achieving spectral resolutions in excess of R~100,000 on ELTs. Despite its high spectral resolution, the concept instrument has modest dimensions, and allows high throughput. We discuss simulations results, suggesting that such an instrument can reduce the number of observed transits needed for molecular oxygen detection by 30% and more. Finally, we discuss design parameters and the unique aspects that need to be taken into account in the design of such an instrument, and present initial data from a lab pathfinder demonstrating its capabilities.

        Speaker: Dr Sagi Ben-Ami (Smithsonian Astrophysical Observatory)
      • 5:45 PM
        Diffraction-Limited Instruments for PRV Measurements and Direct Planet Spectroscopy 20m

        Advances in Adaptive Optics have made it possible to develop a new generation of very high spectral resolution spectrometers R~(100,000-150,000) operating in the deep red and near-IR on large telescopes. These instruments can be used both for precision radial velocity (PRV) measurements when coupled with high precision calibration sources, direct spectroscopy of exoplanets, as well as for a number of general astrophysics science cases.
        Feeding a diffraction-limited beam into a single mode fiber has many advantages: the small A*Omega of a diffraction-limited beam enables a much more compact instrument than a seeing-limited one; a compact instrument is easier to maintain under precise thermal control for high opto-mechanical stability; the use of single mode fibers eliminates mode scrambling and many PRV error budget terms related to instrument point spread function and telescope pointing; and finally a compact instrument is inherently lower cost than a seeing-limited one.
        We are presently integrating a prototype PRV instrument, Palomar Advanced Radial Velocity Instrument (PARVI), for the Palomar 5-m telescope, and designing another PRV instrument, HISPEC, for Keck, to be pathfinders for diffraction-limited spectrographs on future ELTs, like TMT. We will discuss science programs for PARVI and HISPEC as well as the design and development status of both instruments. Finally, we note that on a space-based telescope such as the EarthFinder it would be possible to extend these benefits into visible wavelengths.

        Speaker: Chas Beichman
    • 8:15 AM 9:45 AM
      VIS instruments: (Chair: Isabelle Boisse)
      • 8:15 AM
        ESPRESSO 15m
        Speaker: Prof. Francesco Pepe
      • 8:30 AM
        EXPRES 15m
        Speaker: Ms Lily Zhao
      • 8:45 AM
        MINERVA-Australis and SONG: New PRV Observatories in Australia 15m

        NASA's Transiting Exoplanet Survey Satellite (TESS) will identify
        thousands of planets orbiting nearby bright stars in a two-year survey
        beginning in the Southern sky. MINERVA-Australis at USQ's Mount Kent
        Observatory is the only southern hemisphere precise radial velocity
        facility wholly dedicated to follow-up of TESS planets. Mass
        measurements of these planets are critically necessary to maximise the
        scientific impact of the TESS mission, to understand the composition of
        exoplanets and the transition between rocky and gaseous worlds.
        MINERVA-Australis is now operational at the University of Southern
        Queensland's Mount Kent Observatory, with three of the planned six 0.7m
        telescopes in place. I present first precise radial velocity results and
        orbital solutions for TESS planets, and give an update on the
        performance of MINERVA-Australis.

        The Stellar Observations Network Group (SONG) is establishing a node at
        Mount Kent. SONG-Australia will complete the global longitude coverage,
        delivering breakthroughs in fundamental understanding of the interiors
        of stars for decades to come. SONG-Australia is designed on a "MINERVA"
        model, whereby fibres from multiple small telescopes feed a single
        high-resolution spectrograph. As a result of these innovations,
        SONG-Australia is expected to be fully operational by late 2019. I
        present results from the Tenerife SONG node which is delivering 1 m/s
        precision velocities.

        Speaker: Prof. Rob Wittenmyer (University of Southern Queensland)
      • 9:00 AM
        The Veloce Doppler Spectrograph at the AAT 15m

        Veloce is a new precision Doppler spectrograph for the 3.9m Anglo-Australian Telescope sited on Siding Spring Observatory in Australia. Cost considerations for an instrument with a total budget of A$5.4m mean that Veloce's design philosophy is one of "just enough" stabilisation (i.e. stabilising the spectrograph in pressure and temperature so that changes over time will be small and linear) combined with simultaneous calibration in every exposure. It uses a fibre-optic integral-field unit to reformat a 2.5" aperture into a 19 fibre x 0.5" slit at the spectrograph entrance, plus 5 sky fibres and two fibres for simultaneous calibration using either a ThXe arc lamp, or a Menlo Systemsastro comb (delivered directly into the spectrograph by an endlessly single-mode fibre). The main fibre run comprises octagonal fibres passing through two fibre agitators, which are then fused to circular fibres before injection into the spectrograph. The spectrograph's first Rosso camera covers 600-930nm, with two additional cameras (Verde and Azzurro) funded for installation in 2019 to provide complete coverage from 380-930nm in a single exposure. The optical performance of the Rosso camera (which started operation in September) is excellent, with the average FWHM of images from the singe-mode astrocomb being less than 1 pixel over the whole echellogram. While processing the IFU data has provided challenges, early results are very promising, and by EPRV IV I hope to be able to highlight recent TESS mass measurement results from Veloce.

        Speaker: Prof. Chris Tinney (UNSW Sydney)
      • 9:15 AM
        First results from PEPSI 15m

        We present recent results from the latest addition to the spectrograph zoo: PEPSI, the new bench-mounted fiber-fed and stabilized “Potsdam Echelle Polarimetric and Spectroscopic Instrument” for the 11.8m Large Binocular Telescope (LBT). Besides the LBT the instrument is also fiber linked to a disk-integration solar telescope and the Vatican Observatory's 1.8m VATT. I will introduce PEPSI and focus on first data and results in order to "feel the taste". Among the first targets were the Sun and solar twins, Gaia benchmark stars, Jupiter's Io, planet-host stars with hot Jupiters as well as stars with Earth-sized planets, novae, the ISM, and much more.

        Speaker: Prof. Klaus Strassmeier (AIP)
      • 9:30 AM
        NEID 15m
        Speaker: Dr Paul Robertson
    • 9:45 AM 10:15 AM
      Coffee break 30m
    • 10:15 AM 12:00 PM
      NIR instruments: (Chair: Ansgar Reiners)
      • 10:15 AM
        The CARMENES radial velocity instrument: performance and results 15m

        The CARMENES high-precision spectrometer started operations in January 1, 2016 at the 3.5-m telescope of the Calar Alto Observatory. Since then, the CARMENES consortium is carrying out a 750-night survey searching for exoplanets around M dwarf stars, preferably in their habitable zones, using the radial velocity technique. CARMENES has the unique capability of providing continuous high-resolution spectroscopy in the visible and the near-infrared wavelength range, from 0.52 to 1.71 micron. The first 3 years of observations have demonstrated the excellent performance of CARMENES and have provided us with insight into the exploitation potential of its visible and near-infrared channels. A number of exoplanets have been published so far and observations continue for tens of bona-fide planet candidates. CARMENES is also showing its potential as a workhorse in the study of exoplanet atmospheres. In this talk I will discuss the CARMENES performance, focusing in particular on the near-infrared channel, and highlight the main results obtained during the first 3 years of operations.

        Speaker: Dr Ignasi Ribas (ICE/CSIC & IEEC)
      • 10:30 AM
        IRD: Infrared PRV instrument for the Subaru Telescope 15m

        The Infrared Doppler (IRD) instrument is a fiber-fed high-resolution near-infrared spectrometer for the Subaru 8.2-m telescope covering the Y-, J-, and H-bands simultaneously with a spectral resolution of ~70,000. It aims at achieving measurement precision of 1-2 m/s in radial velocity (RV) with a very stable spectrograph and an original laser frequency comb. The most effective astronomical targets of IRD are M dwarfs, especially late-M dwarfs, which are too faint to observe at optical wavelengths even with such a large telescope. IRD's commissioning at the summit started in March 2017 and first light observations were successfully carried out in August 2017. A Subaru Strategic Program (SSP) survey has started from 2019A. We report the current status of the instrument and the planned survey.

        Speaker: Dr Takayuki KOTANI (ABC/NAOJ)
      • 10:45 AM
        HPF 15m
        Speaker: Dr Joe Ninan
      • 11:00 AM
        SPIRou spectropolarimeter in operation at CFHT 15m

        The near-infrared spectropolarimeter SPIRou is now in operation on the 3.6-m Canada-France-Hawaii telescope and recently started its survey. Thanks to its unique combination of a wide simultaneous spectral domain (0.98-2.35 μm, YJHK bands), a high throughput (>10% in H and K bands), a resolving power of 70’000, a radial-velocity precision close to 2 m/s, and polarimetric capabilities, SPIRou is expected to play a key role on the detection and characterization of planetary systems around nearby M dwarfs. Here we present the main characteristic of the instrument and the main results obtained during commissioning.

        Authors: Jean-François Donati, Claire Moutou, François Bouchy, Etienne Artigau, Isabelle Boisse, Andres Carmona, Neil Cook, Xavier Delfosse, René Doyon, Pascal Fouqué, Melissa Hobson, and the SPIRou team

        Authors: Jean-François Donati, Claire Moutou, François Bouchy, Etienne Artigau, Isabelle Boisse, Andres Carmona, Neil Cook, Xavier Delfosse, René Doyon, Pascal Fouqué, Melissa Hobson, and the SPIRou team

        Speaker: François Bouchy
      • 11:15 AM
        Radial velocities with GIANO-B, the NIR spectrograph at TNG 15m

        The NIR high resolution spectrograph GIANO, working in the wavelength range from 0.97 to 2.45 microns at a resolution of 50,000, was installed and commissioned at the Nasmyth-A focal station of the TNG in 2014. Through the GIARPS project, aimed to the simultaneous use of GIANO and HARPS-N spectrographs, GIANO was moved to the Nasmyth-B (re-naming the instrument GIANO-B) and modified in its configuration. This also provided a significant improvement in the instrument performances. GIANO-B, together with HAPRS-N, is carrying out a radial velocity survey searching for and characterising Hot Jupiters around young stars. We present the GIANO-B RV performances and the results obtained during the first year of observations.

        Speaker: Dr Ilaria Carleo
      • 11:30 AM
        iLocater: Moving from design to fabrication 15m

        iLocater is a next-generation precision radial velocity spectrograph under development for the Large Binocular Telescope (LBT). The instrument has three major subsystems which are currently undergoing simultaneous development: a single-mode fiber fed high-resolution (R~150,000-240,000) NIR echelle spectrograph, an adaptive optics fed fiber-injection system, and a fabry-perot etalon based wavelength calibration unit. We present a design, performance and status update for iLocater and its individual subsystems as the instrument moves from design to fabrication.

        Speaker: Dr Jonathan Crass (University of Notre Dame)
      • 11:45 AM
        Precise Near Infrared Radial Velocities With iSHELL 15m

        We present our radial-velocities (RVs) with the iSHELL spectrograph at the NASA Infrared Telescope facility. Replacing the 25 year old CSHELL instrument, iSHELL offers improvements in spectral grasp (~40x), resolution (70,000 versus 46,000), throughput, optics, and detector characteristics. Our primary goal with iSHELL is to characterize the precise radial-velocity performance of the methane isotopologue absorption gas cell in the calibration unit. Over the last two years, we've obtained 3-12 epochs of bright nearby RV standards as well as RV variables of our own. A new flexible telluric model allows for dynamic abundance ratios in Earth's atmosphere, and physically-motivated analytic fringing models account for internal reflections from the optics in the instrument. We've demonstrated 6 m/s precision on Barnard’s star over one year, sufficient to confirm Neptune-mass planets around M Dwarfs discovered by the NASA TESS mission. With further development on the the non-standard blaze and line spread functions present in iSHELL data, we aim to achieve 3-5 m/s long-term precision, sufficient to detect terrestrial mass planets in the habitable zone of nearby M Dwarfs.

        Speaker: Prof. Peter Plavchan (George Mason University)
    • 12:00 PM 6:00 PM
      Free time and social activities 6h
    • 9:00 AM 10:00 AM
      Future EPRV instruments: (Chair: Dave Latham)
      • 9:00 AM
        NIRPS on track to join HARPS on the ESO 3.6-m 15m

        The Near-InfraRed Planet Searcher (NIRPS) is a new ultra-stable near-infrared (YJH) spectrograph that will be installed on ESO 3.6-m Telescope in La Silla, Chile in begining 2020. Covering YJH bands with a spectral resolution of 100’000, NIRPS is part of a new generation of adaptive optics fiber-fed spectrographs. NIRPS will use a 0.4-arcsecond multi-mode fiber, half that required for a seeing-limited instrument, allowing a spectrograph design that is half as big as that of HARPS, while meeting the requirements for high throughput and high spectral resolution. A 0.9-arcsecond fiber will be used for fainter targets and degraded seeing conditions. NIRPS is designed to achieve a precision of 1 m.s-1 and will be operated simultaneously with HARPS. Here we describe the NIRPS main technical characteristics and the first tests of the Cassegrain Adapter made in lab with the AO system.

        Authors: François Bouchy, René Dyon, François Wildi, Etienne Artigau, Nicolas Blind, Isabelle Boisse, Bruno Canto Martins, Bruno Chazelas, Ryan Cloutier, Xavier Delfosse, Xavier Dumusque, Pedro Figueira, Jonay Gonzales Hernandez, Christophe Lovis, Claudio Melo, Francesco Pepe, Rafael Rebolo, José Renan De Meideiros, Nuno Santos, Stéphane Udry, Gregg Wade, and the NIRPS team

        Speaker: Prof. Bouchy François
      • 9:15 AM
        HARPS 3 15m
        Speaker: Dr Sam Thompson
      • 9:30 AM
        Better Radial Velocity Measurement Precision Through Organic Chemistry: The GMT Consortium Large Earth Finder (G-CLEF) 15m

        The GMT-Consortium Large Earth Finder (G-CLEF), is currently scheduled to be the first PRV-capable instrument on an ELT. G-CLEF embraces many design paradigms of earlier PRV instruments, especially the HARPSs. However, the G-CLEF design team is exploiting several novel technologies to deliver an exceptionally stable and calibratable spectrograph. In this talk, we provide an overview of the G-CLEF instrument, the challenges associated with designing a PRV instrument for ELT-scale apertures and then focus on those innovative design features of G-CLEF that should make it an exceptionally precise stellar velocimeter.

        Speaker: Dr Andrew Szentgyorgyi (Smithsonian Astrophysical Observatory)
      • 9:45 AM
        MAROON-X: An Earth-Finder Spectrograph for the Gemini Observatory 15m

        Exoplanet surveys have recently progressed to the point of discovering small, potentially terrestrial planets orbiting in circumstellar habitable zones. Assessing the true degree of habitability of these worlds requires gaining knowledge of both their bulk and atmospheric properties. In this talk I will summarize the development of MAROON-X, which is a high precision radial velocity spectrograph that is scheduled to be commissioned at Gemini North as a visitor instrument in early 2019. MAROON-X is designed to measure the masses, and thus constrain the densities of potentially Earth-like worlds around late M dwarfs. I will describe how MAROON-X will be used in conjunction with facilities like TESS, JWST, and the ELTs to make the first credible searches for habitable environments beyond our Solar System.

        Speaker: Dr Julian Stuermer
    • 10:00 AM 10:30 AM
      Other: (Chair: Dave Latham)
      • 10:00 AM
        Precision NIR RM effect observations with the Habitable-zone Planet Finder 15m

        Significant progress has been made in recent years in measuring the sky-projected obliquity distribution of early-type planet hosting systems via precise Rossiter-McLaughlin (RM) effect observations. However, currently only two M-dwarf systems, GJ 436 and Kepler-45, have published obliquities—and interestingly GJ 436 is observed to be misaligned. With such a sparse sample, key questions remain about the dynamical histories of M-dwarfs at the fully convective boundary. The advent of stabilized extremely precise RV spectrographs in the near-infrared (NIR) are opening the doors to answering these questions, capitalizing on the large RM-effect amplitudes produced by transiting exoplanets orbiting around rapidly-rotating M-dwarfs. In this talk, we will discuss recent precision RM effect observations of fully-convective M-dwarfs with the Habitable-zone Planet Finder (HPF), a stabilized NIR spectrograph recently commissioned on the 10m Hobby-Eberly Telescope (HET) at McDonald Observatory. We will discuss recent RM effect observations of the transit of TRAPPIST-1b, early results of which are consistent with a well-aligned orbit. We will discuss the merits and limitations of the HET/HPF queue to observe RM effects of M-dwarfs, utilizing the excellent stability of HPF, large collecting area of HET, and the short transit durations of M-dwarf planets. Finally, we will discuss future planned observations in the TESS era, with TESS being expected to discover a multitude of M-dwarf planet systems favorable for precise RM effect measurements in the NIR.

        Speaker: Mr Gudmundur Stefansson (Penn State University)
      • 10:15 AM
        A fundamental test of planet formation: searching for low-mass planets around metal-poor stars 15m

        As the number of known super-Earths and Neptune-like planets keeps growing, the properties and frequency of such systems start to be revealed. Planet formation models suggest that these low-mass planets, unlike giant planets, should be frequent around stars with low metallicities. But this theoretical prediction still needs to be observationally confirmed.
        I will present the analysis of a decade-long radial-velocity survey of metal-poor stars with the HARPS spectrograph. In this survey, we find a significantly lower frequency of low-mass planets, when compared with results for stars with solar metallicity. These results challenge the predictions of the standard core-accretion theory, strengthening the idea that planets with lower masses which form in metal-poor disks may not migrate far before the disk dissipates, ending up at larger orbital periods and thus being still undetectable.

        Speaker: João Faria (Institute of Astrophysics and Space Sciences)
    • 10:30 AM 11:00 AM
      Coffee break 30m
    • 11:00 AM 12:30 PM
      From raw spectra to EPRV: RV pipeline: (Chair: Christophe Lovis)
      • 11:00 AM
        Review: RV pipelines 30m
        Speaker: Dr Arpita Roy
      • 11:30 AM
        Automated data reduction pipelines for the HPF and NEID spectrometers 20m

        The precision radial velocity community is pushing spectrometer hardware to new and ever more exciting stability levels that support a velocity precision of ~1 m/s in the near-infrared, and sub 50 cm/s in the visible. These developments must be backed by increasingly sophisticated software algorithms and data reduction pipelines that can realize the potential of the new instruments. I will describe the pipelines that we have developed for the HPF (0.8 - 1.3 microns) and NEID (0.38 - 0.92 microns) PRV spectrometers. This will include algorithmic advances that allow us to more fully exploit our astronomical data, and automation techniques that simplify the user experience in going from on-sky observations to reliable radial velocities. Some of the algorithms we are utilizing include sophisticated up-the-ramp image processing for HPF's H2RG detector, polygon clipping image rectification and alias correction, and synthetic modeling of telluric absorption and emission. I will also touch on computational challenges that we have encountered in developing the NEID pipeline, particularly in light of the instrument's very large band-pass, and subsequent large data volume. The HPF pipeline has been regularly running since summer 2018, while the NEID pipeline will be ready for deployment coincident with instrument commissioning in 2019.

        Speaker: Chad Bender (University of Arizona)
      • 11:50 AM
        Unveiling Iodine-Calibrated RV Spectroscopy 20m

        An iodine cell placed in the light path of a high-resolution spectrograph can
        act as a simultaneous wavelength and point-spread-function fiducial which
        enables precise radial velocities to be extracted from un-stabilized or
        slit-fed spectrographs. This technique enabled the detection and
        characterization of many of the first known exoplanets and played a significant
        role in establishing the study of exoplanets as a subfield of astronomy.
        However, the pipelines needed to extract precise velocities from the data are
        extremely complex and generally treated as a "black boxes" for many end users. I
        will explain the methodology of the iodine technique in detail and unveil some
        aspects often pushed under the rug. I will show some of the sources of
        systematic noise present in the final velocities and describe potential avenues
        for the removal of these systematics from the vast library of archival data. I
        will discuss some of the limitations inherent to the technique, paths to improve
        iodine-based instrumentation, and the role of iodine RV spectroscopy in the

        Speaker: Benjamin Fulton (California Institute of Technology)
      • 12:10 PM
        Using Gaussian processes for precise and robust radial velocity extraction 20m

        Thanks to a number of technical developments, the precision of RV surveys has been steadily improving. While the spectrographs of fifty years ago yielded RVs with errors in excess of 1 km/s, today's state-of-the-art stabilised spectrographs boast 10 cm/s precisions. Yet very little has changed in the way individual RVs are actually extracted from observed spectra: i.e., cross correlating observed spectra with a weighted template. This approach suffers a few notable drawbacks, including that

        1. a given template will generally be an imperfect match to any observed star's spectrum;
        2. information is discarded when computing RVs;
        3. the RV extraction process is sensitive to stellar activity variability and telluric contamination; and
        4. acquiring more spectra does not improve the accuracy or precision of existing RVs, despite the additional spectra containing potentially-useful new constraints.

        I'll present a new data-driven approach for extracting RVs that aims to address these drawbacks. The new method models each spectrum in an ensemble of spectra with a Gaussian process (GP), then aligns each GP model with every other GP model spectrum. In so doing, the method effectively builds up a super-resolved, low-noise template spectrum, and is incidentally also able to yield RVs that are less sensitive to stellar activity and telluric contamination than RVs extracted with more conventional approaches.

        This new method is conceptually simple, and its performance very favourable using both synthetic and real data. As such, it has the potential to enable the study of smaller planets around a wider variety of stars than has previously been possible. It could also be fruitfully applied to archival data.

        Speaker: Dr Vinesh Maguire-Rajpaul (University of Cambridge)
    • 12:30 PM 2:00 PM
      Lunch 1h 30m
    • 2:00 PM 3:45 PM
      Splinter Calibration challenges: (Organiser: Christian Schwab)
    • 2:00 PM 3:45 PM
      Splinter Computational and statistical methods 2: (Organiser: Nathan Hara, Sophia Sulis)
    • 2:00 PM 3:45 PM
      Splinter Observational strategies: (Organiser: Xavier Dumusque)
    • 3:45 PM 4:30 PM
      Coffee break 45m
    • 4:30 PM 4:45 PM
      NASA Exoplanet Exploration Program and precision radial velocity 15m
      Speaker: Dr Eric Mamajek (Jet Propulsion Laboratory)
    • 4:45 PM 5:00 PM
      Best poster presentation (Jacob Luhn) + Adjourn 15m