17-21 March 2019
Sunstar Hotel, Grindelwald, Switzerland
Europe/Zurich timezone

Splinter Sessions

Monday 14:00 - 15:45

EPRV Pipelines: "From Raw Spectra to EPRV" (organiser: Arpita Roy)

This session will comprise of an Instrument Pipeline Roundtable, where we discuss the choices made by different instrument teams in dealing with challenging pipeline modules (eg. wavelength calibration, detector imperfections, RV calculation). In order to make this conversation most productive, we have invited representatives from each instrument with deep knowledge of the pipeline development to be present. We will thus learn about successes and hurdles faced both commonly and uniquely by next-generation spectrographs on the path to extreme precisions, and consider mitigation strategies and code sharing strategies going forward.

A list of the pipeline representative and people that might attend can be found here

EPRV in NIR (organiser: Joe Ninan)

This session is planned as a set of mini presentations and discussions by each NIR instrument team about the major challenges they face in their NIR instrument and how they solved or plan to solve it.

The lead representative of each instruments will present one or two slides, which will then be used for discussion. The main topics that will be discussed are persistence, detector stability, intra-pixel QE variations, etc..

A list of the pipeline representative and people that might attend can be found here

We would like to invite you to the EPRV's splinter session on stellar activity in Sun-like stars and M dwarfs, to be held on Monday 18 March between 14:00-15:45. Stellar activity is currently a major obstacle to EPRV, and to overcome this barrier it is necessary that we understand the physical processes at play on the surfaces of the host stars. 

Stellar activity in Sun-like stars and M-dwarfs (organiser: Heather Cegla and Raphaëlle Haywood)

The splinter will begin with three talks:

• Sudeshna Boro-Saikia: Magnetic activity, rotation and magnetic cycles of Sun-like stars
• Elisabeth Newton: Magnetic activity and rotation of M dwarfs
• Warrick Ball: The impact of oscillations and granulation on high precision Res

The remaining 45 minutes will be a mix of small-group and full-group discussions. Our goal is to encourage productive exchanges among us all, conducive to developing new ideas on how to break the activity barrier in EPRV in coming years!

The following experts on stellar activity will be present to guide discussions:
Isabelle Boisse, Nadège Meunier, Sophia Sulis, and Johanna Teske.


Tuesday 14:00 - 15:45

Joint Splinter Session: Stellar activity and statistics (organisers: Heather Cegla, Nathan Hara, Raphaëlle Haywood and Sophia Sulis)

In order to obtain precise and accurate masses for super-Earths and even sub-Neptunes, it is imperative that we account for the RV signals induced by the host stars’ intrinsic magnetic activity. The current best solution is to treat activity as correlated noise.

The splinter will begin with 4 talks:
• Molly Kosiarek: Using Gaussian Processes to Mitigate Stellar Noise
• David Montes: Identifying chromospheric activity-sensitive spectral lines in the CARMENES VIS and NIR spectral range of M dwarfs
• Mario Damasso: Assessing the accuracy of planetary mass determinations through radial-velocity simulations in the presence of stellar activity
• Howard Isaacson: Activity De-correlation of Individual Spectral Lines

Following the talks there will be an hour for discussion. Some of the questions that we will tackle include (but are not limited to):

• What aspects of stellar signals are statistically well modelled? Which ones are not? 
• Can we conclude on the nature of a signal even if the stellar noise is not well understood/modelled?
• Accounting for stellar activity as correlated noise via Gaussian process regression: what covariance representation can we use?

The following panel of experts will guide the discussion: 
Xavier Dumusque, Vinesh Maguire-Rajpaul and Annelies Mortier.

Telluric contamination in EPRV (organizer: Evangelos Nagel)

We will begin with four short presentations focusing on two different correction strategies:
forward-modelling on the one hand and data-driven on the other. These talks should first give you an overview of the state-of-the-art approaches to correct for telluric features in "out in the wild" (using the expression established by Christian Schwab) instruments like CARMENES and EXPRES, and second, form a basis for a fruitful discussion. During the discussion the participants are encouraged to share their personal experiences and problems with the treatment of telluric lines in their analyses of EPRV data. In the link below, you will find a google document where you can write down questions, remarks, comments, problems, that should be discussed in the splinter. We will finish with a brainstorming session to come up with a list of things we, as a community, need to make progress on telluric correction (e.g. better algorithms, hybrid methods (physics + data-driven), better lab data on water, ...).

Please add some questions related to telluric correction in the following Google doc


14:00-14:05: Introduction
14:05-14:20: Evangelos Nagel "Tellurics@CARMENES"
14:20-14:35: Solène Ulmer-Moll "To which precision can we correct tellurics in the NIR?"
14:35-14:50: Debra Fischer "Tellurics@EXPRES"
14:50-15:05: Megan Bedell "Wobble"
15:05-15:45: Open discussion (e.g. questions from google doc) + brainstorming session

Thursday 14:00 - 15:45

Calibrations challenges for EPRV (organiser: Christian Schwab)

EPRV is nearly upon us, and I would like to invite you to join the calibration splinter on Thursday afternoon. The topic will be "State of the art of precision wavelength calibration - calibrators, extraction software, and the interface between them". There is of course the software splinter as well, so we would like to make any software discussion specific to the calibration source, with the idea that we understand better what the possibilities and implications of different choices are. 

On the hardware end, it would be great to get a comprehensive overview of the calibrators "out in the wild"; what people are using, what precision they get and what the experiences with running the various techniques are. 

To facilitate the discussion and give us an overview of where things stand, we will start with very short, workshop-style presentations. If you would like participate, please send me ~3-5 slides (3min) as pdf to be incorporated into one large slide deck. I would ask that these not be polished presentations, but honest, detailed showcases of capabilities, limitiations, current problem(s) being worked on, and lessons learned. We can assume that everyone in the room knows the various techniques, so we can drop the introductions and get into the interesting bits right away. Please have the value of what you want to present to this particular audience in mind when you put together the slides. 

I am personally excited to hear about what the sticky points are that people struggle with right now, and am looking forward to a lively discussion. To help that along, I have set up a google doc to collect suggestions for discussion topics, and questions. to get us started. Please take a minute to add a question you'd like to discuss, and I will collate them into a few broad topics if possible. I have also added a section where you can indicate that you want to present, and on what instrument or technology. 

It would be fantastic to have every instrument team represented, and presenting what they do. I hope you join!

Computational and statistical methods (organisers: Nathan Hara and Sophia Sulis)

During this splinter session, we will cover different statistical methods to analyse RV data. We will first have one hour of presentation given by experts in the field, followed by a 45-minute discussion.

• Eric Ford (remote)
• Rodrigo Diaz (remote)
• Michael Cretignier
• Shay Zucker

Observational strategies (organiser: Xavier Dumusque)

During this splinter session, we will discuss the impact of observational strategies on the recovery of planetary signals. This is extremely important in the framework of TESS where the period of the signal to characterise are well known. This problem seems simple, however, once adding stellar signals that can perturb radial-velocity measurements, everything gets more complicated. The idea of this splinter is to discuss 

After a few talks from experts for about 45 minutes we will open the discussion to the audience in the goal of answering to the following questions (and others):
• Can we define a general observational strategy, or should it be defined case by case?
• Would it be possible as a community to collaborate on a few very exciting TESS targets?
• Can we use statistical methods to predict when we should observe a given target?
• Is it better to spend more time on a small number of targets to characterise them with good precision, or to confirm more candidates but at less precision?

You are welcome to post your own questions/ideas here.

• Jeniffer Burt: RV follow up of the earliest TESS planets
• Pedro Viana: Optimal scheduling of radial velocity follow-up of transiting exoplanets
• Johanna Teske: A Southern Hemisphere RV Follow-up Program for TESS with PFS2/Magellan