galstreams: A Library of Milky Way Stellar Stream Footprints and Tracks

Nearly a hundred stellar streams have been found to date around the Milky Way and the number keeps growing at an ever faster pace. Here we present the galstreams library, a compendium of angular position, distance, proper motion and radial velocity track data for nearly a hundred (95) Galactic stellar streams. The information published in the literature has been collated and homogenised in a consistent format and used to provide a set of features uniformly computed throughout the library: e.g. stream length, end points, mean pole, stream's coordinate frame, polygon footprint, and pole and angular momentum tracks. We also use the information compiled to analyse the distribution of several observables across the library and to assess where the main deficiencies are found in the characterisation of individual stellar streams, as a resource for future follow-up efforts. The library is intended to facilitate keeping track of new discoveries and to encourage the use of automated methods to characterise and study the ensemble of known stellar streams by serving as a starting point. The library is publicly available as a Python package and served at the galstreams GitHub repository.