The first step to using Octofitter.jl is to install Julia. If you're used to Python, don't worry –- Julia is easy to install, and you won't need to code anything other than changing your input data.

Installing Julia

Visit the Downloads page, and select the latest stable version for your operating system. This is 1.10.0 at the time of writing. Click the [help] links next to your operating system if you require more detailed instructions.

Installing Octofitter

  1. Start julia in a terminal by running julia
  2. Type ] to enter package-mode (see Julia documentation for more details)
  3. Type add Octofitter Distributions Plots CairoMakie PairPlots

You will need the Distributions,jl package so that you can specify priors for different parameters in your models. Plots.jl is for visualizing your results and is optional. CairoMakie.jl and PairPlots.jl can be used for generating corner plots and are also optional.

Extension Packages

Some Octofitter functionality exists in extension packages, including radial velocity fitting. If you need one of these packages you can install them like so:

pkg> add OctofitterRadialVelocity
pkg> add
pkg> add

These aren't included by default since they may include a number of heavier dependencies that aren't needed by all users. They are descibed further in relevant sections of the documentation.

Fitting your first model

Start with the Fit Relative Astrometry tutorial. It shows how one can model the orbit of one planet based on relative astrometry points.