2020/08/12 by Bryce Bolin, C. Fremling, Bolin, Bryce T. +85 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Planetary Science and Exploration #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2008.05384
openalex publication_date 2020/08/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present time-resolved visible spectrophotometry of minimoon 2020 CD3, the second asteroid known to become temporarily captured by the Earth-Moon system's gravitational field. The spectrophotometry was taken with Keck I/LRIS between wavelengths 434 nm and 912 nm in B, g, V, R, I and RG850 filters as it was leaving the Earth-Moon system on 2020 March 23 UTC. The spectrophotometry of 2020 CD3 most closely resembles the spectra of V-type asteroids and some Lunar rock samples with a reddish slope of ~18%/100 nm between 434 nm and 761 nm corresponding to colors of g-r = 0.62±0.08, r-i = 0.21 ± 0.06 and an absorption band at ~900 nm corresponding to i-z = -0.54±0.10. Combining our measured 31.9±0.1 absolute magnitude with an albedo of 0.35 typical for V-type asteroids, we determine 2020 CD3's diameter to be ~0.9±0.1 m making it the first minimoon and one of the smallest asteroids to be spectrally studied. We use our time-series photometry to detect periodic lightcurve variations with a