Sorcha: Optimized Solar System Ephemeris Generation

TL;DR

Sorcha is a highly efficient solar system survey simulator designed for large-scale surveys like LSST, capable of rapidly calculating on-sky positions for millions of objects, enabling detailed detection estimates.

Contribution

It introduces a novel, optimized algorithm for ephemeris generation that overcomes computational bottlenecks in existing survey simulators for large datasets.

Findings

Efficiently computes on-sky positions for millions of objects.

Accurately identifies survey exposures crossing each object.

Supports detailed detection modeling for large-scale surveys.

Abstract

Sorcha is a solar system survey simulator built for the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) and future large-scale wide-field surveys. Over the ten-year survey, the LSST is expected to collect roughly a billion observations of minor planets. The task of a solar system survey simulator is to take a set of input objects (described by orbits and physical properties) and determine what a real or hypothetical survey would have discovered. Existing survey simulators have a computational bottleneck in determining which input objects lie in each survey field, making them infeasible for LSST data scales. Sorcha can swiftly, efficiently, and accurately calculate the on-sky positions for sets of millions of input orbits and surveys with millions of visits, identifying which exposures these objects cross, in order for later stages of the software to make detailed estimates of the apparent magnitude and detectability of those input small bodies. In this paper, we provide the full details of the algorithm and software behind Sorcha's ephemeris generator. Like many of Sorcha's components, its ephemeris generator can be easily used for other surveys.