Software

Octofitter

Octofitter is a large set of packages I created with the goal of advancing the current state of orbit fitting. Octofitter is built from the ground-up for extremely high performance and differentiable computing. Using Octofitter, challenging orbit models which previously would require hours or days, can now be sampled in seconds or minutes.

This speed enables researchers to approach their modelling tasks with a new level of rigour, and following a full Bayesian workflow. One can—in less than the time it used to take to run a single model—compare how different individual data points impact a fit, compare how priors affect the results, or even run full suites of simulated fits to anticipate how new data would impact findings.

Octofitter supports an even-growing list of kinds of exoplanet data. At present, these include:

• Relative astrometry
• Barycentric radial velocity (e.g. of a star)
• Barycentric radial velocity (e.g. of a star)
• Hipparcos-Gaia proper motion anomaly
• Hipparcos IAD
• Relative photometry
• Absolute photometry
• Direct images
• Interferometric closure phases and squared visibilities e.g. from sparse aperture masking
• GRAVITY closure phase data using kernel phase analysis
• Arbitrary x vs. y likelihood maps e.g. from GRAVITY, spectral cross correlation, etc.
• Some spectral modelling features, e.g. to support GRAVITY data

In addition, all of the above data can be combined together through a user-specified joint model. These models can freely incorporate the following features:

• Tie dynamical masses and photometry together through age & cooling tracks
• Specify custom priors, including multivariate priors with correlations, etc.
• Specify prior distributions using kernel density estimates (just pass raw samples).
• Freely transform variables to different bases

PairPlots

PairPlots is a Julia and Python package for generating pair plots, also known as corner plots. Inspired by the very popular Python package corner.py, this package produces highly customizable visualizations to compare high-dimensional data e.g. Markov-chain monte carlo posteriors.

PlanetOrbits

PlanetOrbits.jl is the calculation backend for Octofitter. It provides an easy interface to a large suite of different orbit calculations, and is fully auto-differentiable.

PlanetOrbits.jl supports many different kepler solvers with varying accuracies and number types (e.g. Float-16, Float-32, Float-64, and arbitrary precision). Bound and unbound (hyperbolic) orbits are supported.

AstroImages

AstroImages.jl is a package for loading and displaying FITS files, complete with support for world coordinate systems. It's very simple to use:

img = load("myfile.fits",1)
img["HEADER1"] = 1.0
img["HEADER1",/] = "comment 1"
imview(img, stretch=logstretch)
        

JuliaAstro

I help maintain some of the Julia Astro packages, and the main documentation and tutorial site: http://juliaastro.org.

Julia RTC

For the SPIDERS instrument, I developed a Julia-based real time computing framework. This framework is based around the ultra-low latency aeron framework developed for high-frequency trading.

Our Julia RTC framework is competitive with hand-written C, but far easier to use.

You can read more about the framework in our SPIE proceeding: https://arxiv.org/abs/2407.07207.

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