Layup: orbit fitting at LSST Scale

Starting later this year, the Vera C. Rubin’s Observatory’s Legacy Survey of Space and Time (LSST) will begin discovering millions of new Solar System objects, ranging from the closest near-Earth asteroids to the most distant trans-Neptunian objects.  Fitting the orbits of those objects (the process of taking the observed on-sky positions and velocities of newly discovered moving Solar System objects and transforming them into orbital parameters) is essential to LSST Solar System science.  To address this challenge, we present Layup, a modern and open-source orbit fitting software suite built in Python and C++, driven with the ephemeris quality orbit integrator ASSIST (Holman et al 2023) and built in collaboration with the LINCC Framework team of software engineers, as part of their Incubator program. In addition to handling the large data volume expected from LSST, Layup also has the capability to handle observations from shift-and-stack and ranging data, routines for converting orbits and uncertainties across different formats, and a special-purpose integrator to derive cometary semi-major axes upon entry in the planetary region, as well as accurate, publication quality visualization tools.