# Development Instructions¶

## Source dependencies¶

If you are building ligo.skymap from source, then in addition to the requirements in the quick start section, you will also need:

## Building from source¶

To build ligo.skymap from source, first clone the git repository:

$git clone https://git.ligo.org/lscsoft/ligo.skymap.git  Then install it with pip: $ pip install .


## Environment variables that control the build¶

There are several environment variables that control the build. To activate one of these options, set it to any non-empty value when you run pip install, like this:

\$ env LIGO_SKYMAP_USE_SYSTEM_CHEALPIX=1 pip install .


Here is the full list of environment variables.

LIGO_SKYMAP_USE_SYSTEM_CHEALPIX

Use the system installation of chealpix rather than building chealpix from the bundled source code.

LIGO_SKYMAP_USE_ITTNOTIFY

Compile and link against the Intel® Instrumentation and Tracing Technology (ITT) API to add tracepoints for performance measurement using Intel® VTune Profiler.

LIGO_SKYMAP_DISABLE_OPENMP

Disable OpenMP parallelization.