The ligo.skymap package requires Python 3.8 or later.

On Linux or macOS x86_64 systems, we recommend installing ligo.skymap using pip or conda, either of which will automatically install all of the additional Python dependencies.

(On other operating systems and architectures, you can install from source.)

Option 1: pip

To install ligo.skymap using pip, you will need pip 19.3 or later. You can check what version of pip you have by running this command:

$ pip --version
pip 20.0.2 from /usr/local/lib/python3.8/site-packages/pip (python 3.8)

If your version of pip is too old, then you can update pip to the most recent version by running this command:

$ pip install --upgrade pip

Then, just run this command:

$ pip install ligo.skymap

You are now ready to get started using ligo.skymap.

Option 2: conda

If you are using the Anaconda Python distribution or the lightweight Miniconda version, you can install ligo.skymap using conda. First, enable the conda-forge repository by running these commands:

$ conda config --add channels conda-forge
$ conda config --set channel_priority strict

Then, run this command:

$ conda install ligo.skymap

You are now ready to get started using ligo.skymap.


When you use pip to install ligo.skymap with pip or conda, it will automatically install the following required Python packages:

The following packages are optional for specific features:

  • pytest for running the test suite

Optional LALSimulation Data

The following instructions are only relevant if you are installing ligo.skymap for the purpose of generating localizations with BAYESTAR (e.g., for analysis of LIGO/Virgo/KAGRA data or for simulations) and you are not using a LIGO Data Grid cluster.

Some gravitational waveform approximants in LALSuite (notably, reduced order models) rely on external data files. These data files are part of lalsuite-extra, which must be installed separately. To install these data files, run the following commands:

$ curl -O
$ tar xf lalsuite-extra-1.3.0.tar.gz
$ cd lalsuite-extra-1.3.0
$ ./configure --prefix=$HOME/.local
$ make install

Then, add the following line to your shell profile script (~/.profile, ~/.bashrc, or similar):

export LAL_DATA_PATH=$HOME/.local/share/lalsimulation

Then log out and log back in.