Installation

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 julialang.org 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 CairoMakie PairPlots

You will need the Distributions,jl package so that you can specify priors for different parameters in your models. CairoMakie.jl is used for generating plots and isn't needed if you only want text-based summary outputs. PairPlots.jl (in combination with CairoMakie) is used for generating corner plots and can also be skipped if these aren't of interest.

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 http://github.com/sefffal/Octofitter.jl:OctofitterImages
pkg> add http://github.com/sefffal/Octofitter.jl:OctofitterInterferometry

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

Companion Packages by Use Case

Depending on your analysis, you may need additional packages. Here's a guide organized by task:

For simulating orbital data:

pkg> add PlanetOrbits  # Provides orbit() and radvel() for generating synthetic data

For parallel tempered sampling (multi-modal posteriors) and Bayesian model comparison:

pkg> add Pigeons  # Provides octofit_pigeons() for robust sampling and stepping_stone() for Bayes factors

For radial velocity fitting:

pkg> add OctofitterRadialVelocity

For direct imaging:

pkg> add http://github.com/sefffal/Octofitter.jl:OctofitterImages

For interferometry:

pkg> add http://github.com/sefffal/Octofitter.jl:OctofitterInterferometry

pkg> add Octofitter OctofitterRadialVelocity Distributions CairoMakie PairPlots PlanetOrbits Pigeons

Fitting your first model

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