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Main Authors: Bernstein, Gary M., Najafi, Negin, Gomes, Daniel C. H.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.01184
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author Bernstein, Gary M.
Najafi, Negin
Gomes, Daniel C. H.
author_facet Bernstein, Gary M.
Najafi, Negin
Gomes, Daniel C. H.
contents Using published simulations of the 10-year Legacy Survey of Space and Time (LSST), we forecast its ability to determine the masses of individual main-belt asteroids (MBAs) through precise astrometry of any pairs of the ~1.2 million known MBAs undergoing close gravitational encounters during the survey. The uncertainty $σ_I$ on the impulse applied to a tracer asteroid by its deflector is derived from the Fisher matrix of the tracer's astrometric data, including an azimuthal acceleration $A_2$ from the Yarkovsky effect as a free parameter for each tracer. If only LSST observations are available, $σ_I \approx7\times10^{-6}\,{\rm m}\,{\rm s}^{-1}$ for MBAs at apparent magnitude $m_V<19.5,$ degrading ~10x for $m_V=23.$ These tracers yield a median uncertainty on the mass of an MBA of $\approx4\times10^{-14}M_\odot,$ with a wide range of variation depending on the ``luck'' of close encounters. Roughly 125 MBAs obtain mass measures with S/N>5. If pre-LSST astrometry yields a strong constraint on the state vector of the tracer MBA at the start of LSST, then these values improve to median $σ_M\approx1.3\times10^{-14}M_\odot$ and 310 MBAs at S/N>5, with >1/2 of these having S/N>10. These yields would be a ~10-fold increase in the number of known asteroid masses, including a nearly complete knowledge of MBAs with H<7.5. If pre-LSST data are sufficient to start constraining the Yarkovsky effect, another factor $\sim1.5$ can be gained. Tables of the measurable deflector MBAs and their tracers are provided.
format Preprint
id arxiv_https___arxiv_org_abs_2504_01184
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Determinations of asteroid masses using mutual encounters observed in the Legacy Survey of Space and Time
Bernstein, Gary M.
Najafi, Negin
Gomes, Daniel C. H.
Earth and Planetary Astrophysics
Using published simulations of the 10-year Legacy Survey of Space and Time (LSST), we forecast its ability to determine the masses of individual main-belt asteroids (MBAs) through precise astrometry of any pairs of the ~1.2 million known MBAs undergoing close gravitational encounters during the survey. The uncertainty $σ_I$ on the impulse applied to a tracer asteroid by its deflector is derived from the Fisher matrix of the tracer's astrometric data, including an azimuthal acceleration $A_2$ from the Yarkovsky effect as a free parameter for each tracer. If only LSST observations are available, $σ_I \approx7\times10^{-6}\,{\rm m}\,{\rm s}^{-1}$ for MBAs at apparent magnitude $m_V<19.5,$ degrading ~10x for $m_V=23.$ These tracers yield a median uncertainty on the mass of an MBA of $\approx4\times10^{-14}M_\odot,$ with a wide range of variation depending on the ``luck'' of close encounters. Roughly 125 MBAs obtain mass measures with S/N>5. If pre-LSST astrometry yields a strong constraint on the state vector of the tracer MBA at the start of LSST, then these values improve to median $σ_M\approx1.3\times10^{-14}M_\odot$ and 310 MBAs at S/N>5, with >1/2 of these having S/N>10. These yields would be a ~10-fold increase in the number of known asteroid masses, including a nearly complete knowledge of MBAs with H<7.5. If pre-LSST data are sufficient to start constraining the Yarkovsky effect, another factor $\sim1.5$ can be gained. Tables of the measurable deflector MBAs and their tracers are provided.
title Determinations of asteroid masses using mutual encounters observed in the Legacy Survey of Space and Time
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2504.01184