Title: LEADER: fast estimates of asteroid shape elongation and spin latitude distributions from scarce photometry,
Abstract: Many asteroid databases with lightcurve brightness measurements (e.g. WISE,
Pan-STARRS1) contain enormous amounts of data for asteroid shape and spin
modelling. While lightcurve inversion is not plausible for individual targets
with scarce data, it is possible for large populations with thousands of
asteroids, where the distributions of the shape and spin characteristics of the
populations are obtainable.
We aim to introduce a software implementation of a method that computes the
joint shape elongation p and spin latitude beta distributions for a population,
with the brightness observations given in an asteroid database. Other main
goals are to include a method for performing validity checks of the algorithm,
and a tool for a statistical comparison of populations.
The LEADER software package read the brightness measurement data for a
user-defined subpopulation from a given database. The observations were used to
compute estimates of the brightness variations of the population members. A
cumulative distribution function (CDF) was constructed of these estimates. A
superposition of known analytical basis functions yielded this CDF as a
function of the (shape, spin) distribution. The joint distribution can be
reconstructed by solving a linear constrained inverse problem. To test the
validity of the method, the algorithm can be run with synthetic asteroid
models, where the shape and spin characteristics are known, and by using the
geometries taken from the examined database.
LEADER is a fast and robust software package for solving shape and spin
distributions for large populations. There are major differences in the quality
and coverage of measurements depending on the database used, so synthetic
simulations are always necessary before a database can be reliably used. We
show examples of differences in the results when switching to another database.