2020 Sagan Exoplanet Summer Workshop

Hands-on Sessions

From Pixels to Planets: Finding Planets in Radial Velocity Data

Hands-on Session Developers: BJ Fulton (Caltech/IPAC-NExScI), Nathan Hara (Univ. of Geneva), Heather Cegla (Univ. of Warwick, Univ. of Geneva), Chad Bender (Univ. of Arizona)

The radial velocity technique of exoplanet detection was used to detect most of the first ~1000 exoplanets discovered. While missions relying on the transit technique have surpassed radial velocities in the ability to detect the smallest planets, the radial velocity technique is still critical to measure masses and gain insight into the composition of these planets. Future missions like the James Webb Space Telescope will rely on precise planetary masses to interpret atmospheric spectra and to constrain the molecular composition of those atmospheres. Furthermore, provided the stellar noise sources can be mitigated, radial velocities can unveil terrestrial planets at periods where the transit probability is very low.

For the hands-on sessions, participants will access various tutorials from the Data & Analysis Center for Exoplanets (DACE) platform to learn about how to find planets using the radial velocity technique.

They will use online tutorials and Jupyter notebooks; instructions on how to install the necessary software are provided here. Python proficiency is not required, but some basic knowledge would be beneficial, such as basic syntax and how to use Jupyter notebooks. Participants can use this basic introduction to Jupyter notebooks to prepare (please download the linked ipynb file and view it with the Jupyter notebook software once you have installed Python).

Dr. Nathan Hara of the University of Geneva prepared these DACE tutorials:

Part 4 also has this accompanying slide deck

In addition, there is a DACE cheat sheet and relevant materials (documentation, Jupyter notebooks) for the hands-on sessions.

Hands-on Session Schedule:


Participants will learn how to use the online DACE analysis platform to identify planets in radial velocity time series data and model them using Markov Chain Monte Carlo techniques to extract precision planetary parameters and uncertainties. We will use these tools to re-discover the first known exoplanet, 51 Pegasi.


Participants will learn how to extract radial velocities from high-resolution spectra and dive into the details of planet hunting using the radial velocity technique.

Wednesday and Thursday:

Participants will work on the Planet hunt challenge (if there is enough time on Tuesday, they might start then already). They will be given a real radial velocity dataset with known planets, but not be told the star name or what planets to expect. They will use the tools acquired in the first- and second-day tutorials to identify all planetary signals in the radial velocity dataset. Since the challenge is expected to take a few hours, participants will continue working on their own on Thursday with support from experts being provided virtually over Zoom and Slack.


Participants will report back with the planets they have found, and we will compare and contrast the results and discuss the challenges associated with radial velocity detection of planets.


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(last updated July 28th, 2020 11:02:55)