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lenstronomy is a multi-purpose software package to model strong gravitational lenses. lenstronomy finds application for time-delay cosmography and measuring the expansion rate of the Universe, for quantifying lensing substructure to infer dark matter properties, morphological quantification of galaxies, quasar-host galaxy decomposition and much more. A (incomplete) list of publications making use of lenstronomy can be found at this link.

The development is coordinated on GitHub and contributions are welcome. The documentation of lenstronomy is available at and the package is distributed through PyPI and conda-forge. lenstronomy is an affiliated package of astropy.


PyPI conda-forge

lenstronomy releases are distributed through PyPI and conda-forge. Instructions for installing lenstronomy and its dependencies can be found in the Installation section of the documentation. Specific instructions for settings and installation requirements for special cases that can provide speed-ups, we also refer to the Installation page.

Getting started

The starting guide jupyter notebook leads through the main modules and design features of lenstronomy. The modular design of lenstronomy allows the user to directly access a lot of tools and each module can also be used as stand-alone packages.

If you are new to gravitational lensing, check out the mini lecture series giving an introduction to gravitational lensing with interactive Jupyter notebooks in the cloud.

Example notebooks

We have made an extension module available at You can find simple example notebooks for various cases. The latest versions of the notebooks should be compatible with the recent pip version of lenstronomy.

Affiliated packages

Multiple affiliated packages that make use of lenstronomy can be found here (not complete) and further packages are under development by the community.

Mailing list and Slack channel

You can join the lenstronomy mailing list by signing up on the google groups page.

The email list is meant to provide a communication platform between users and developers. You can ask questions, and suggest new features. New releases will be announced via this mailing list.

We also have a Slack channel for the community. Please send us an email such that we can add you to the channel.

If you encounter errors or problems with lenstronomy, please let us know!


We welcome EVERY contribution from EVERYONE! See our code of conduct.

Check out the contributing page and become an author of lenstronomy! A big shout-out to the current list of contributors and developers!


The design concept of lenstronomy is reported by Birrer & Amara 2018 and is based on Birrer et al 2015. The current JOSS software publication is presented by Birrer et al. 2021. Please cite Birrer & Amara 2018 and Birrer et al. 2021 when you use lenstronomy in a publication and link to Please also cite Birrer et al 2015 when you make use of the lenstronomy work-flow or the Shapelet source reconstruction and make sure to cite also the relevant work that was implemented in lenstronomy, as described in the release paper and the documentation. Don’t hesitate to reach out to the developers if you have questions!