Rigorous Use of Light-curve Inversion and Stellar Occultation Techniques for Deriving a Scaled Three-dimensional Shape for the Jupiter Trojan (911) Agamemnon

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Abstract This work presents a methodology for determining the size, three-dimensional shape, and rotational parameters of small solar system objects, with rigorous uncertainty determination, using stellar occultations, rotational and phase-angle light curves. Here we analyze (911) Agamemnon, considered the third-largest Jupiter Trojan, using five rotational light curves, phase-angle data, and 12 occultations (22 positive chords). The methodology uses a genetic algorithm to compare the rotational data with synthetic light curves from the 3D model, obtaining the uncertainties from the χ 2 minimization. The model is scaled with the occultation data, to calculate dimensions, and the uncertainties. We obtained the first nonconvex model for Agamemnon using the All-Data Asteroid Modeling, considering new rotational, phase-angle, and occultation data. The methodological process was applied to derive the uncertainties, obtaining the rotational parameters λ = 128 . ° 1 ± 0 . ° 8, β = 2 . ° 3 ± 2 . ° 1, P = 6.581797 ± 0.000003 hr, and D S = 156.0 ± 7.8 km, with a σ model of 3 km (indicating the model quality relative to the occultation data). We also used the new data to test the 3D model provided by the Database of Asteroid Models from Inversion Techniques. From the nonconvex shape model rotated to Gaia observation epochs, we derive a geometric albedo of p G = 0.051 ± 0.005 for Agamemnon. The final results also indicate that (911) Agamemnon may be the second-largest known Jupiter Trojan, being smaller than (624) Hektor and larger than (617) Patroclus.

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