PyTransit#

PyTransit is a package for exoplanet transit light curve modelling. It offers optimised CPU and GPU implementations of exoplanet transit models behind a unified interface. Evaluating a model is trivial for simple cases, such as a homogeneous light curve observed in a single passband, and stays straightforward for complex ones, such as heterogeneous light curves containing transits observed in different passbands with different instruments, or transmission spectroscopy.

Development began in 2009 to fill the need for a fast and reliable exoplanet transit modelling toolkit for Python. PyTransit has since gone through several iterations, always aiming to be the fastest and most versatile exoplanet transit modelling tool for Python.

Features#

Highlights

Light curve, passband and epoch indices: variable supersampling, multicolour photometry and TTVs, straight out of the box.

Highlights
RoadRunner model

A fast transit model that works with any radially symmetric limb darkening profile.

RoadRunner model
Transmission spectroscopy

Thousands of wavelength bins sharing one transit geometry, computed once.

Transmission spectroscopy model
Oblate planet

Tens-of-ppm oblateness signals, with the model accuracy dialled to match.

Oblate planet model
Gravity-darkened star

Transits across a flattened, gravity-darkened fast rotator, and the spin-orbit angle their asymmetry reveals.

Gravity-darkened star model
Chromosphere

Transits over a limb-brightened optically thin shell, which inverts the usual shape.

Chromosphere model

Documentation#

Getting started

Install PyTransit and evaluate your first transit model.

Installation
User guide

The model interface, data setup, evaluation, limb darkening, and the OpenCL backend.

User guide
Transit models

The model catalogue: what each model does, when to use it, and its full API.

Transit models
API reference

The transit model base class, limb darkening laws, stellar spectra, contamination, and I/O.

API reference

Citing PyTransit#

If PyTransit contributes to a publication, please cite Parviainen (MNRAS 450, 3233, 2015). The individual models carry their own references, listed on each model’s page under Transit models.

Support#

If you run into difficulties with PyTransit, please open an issue on the GitHub repository. Suggestions and feature requests are welcome through the same route.

License#

PyTransit is licensed under the GPLv3 license.

Indices and tables#