Warning: Synpipe has been removed from the Rubin Observatory LSST Science Pipelines. The last major release with Synpipe included was v20_0_0 in June 2020. Tasks for inserting simulated sources are now provided by pipe_tasks; see community.lsst.org for details.
Synpipe provides tasks which make use of the LSST fake object pipeline to insert realistic galaxies and stars. It also includes scripts to analyze the results of data which has been processed with fake objects inserted.