¹R. J. Curtis,¹H. C. Bates,¹T. J. Warren,¹K. A. Shirley,¹E. C. Brown,¹A. J. King,¹N. E. Bowles
Meteoritics & Planetary Scince (in Press) Link to Article [https://doi.org/10.1111/maps.14055]
¹Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, UK
²Earth Sciences, Natural History Museum, London, UK
Published by arrangement with John Wiley & Sons

A laboratory study was performed using the Visible Oxford Space Environment Goniometer in which the broadband (350–1250 nm) bidirectional reflectance distribution function (BRDF) of the Winchcombe meteorite was measured, across a range of viewing angles—reflectance: 0°–70°, in steps of 5°; incidence: 15°, 30°, 45°, and 60°; and azimuthal: 0°, 90°, and 180°. The BRDF dataset was fitted using the Hapke BRDF model to (1) provide a method of comparison to other meteorites and asteroids, and (2) to produce Hapke parameter values that can be used to extrapolate the BRDF to all angles. The study deduced the following Hapke parameters for Winchcombe: w = 0.152 ± 0.030, b = 0.633 ± 0.064, and h_S = 0.016 ± 0.008, demonstrating that it has a similar w value to Tagish Lake (0.157 ± 0.020) and a similar b value to Orgueil (0.671 ± 0.090). Importantly, the surface profile of the sample was characterized using an Alicona 3D® instrument, allowing two of the free parameters within the Hapke model φ and �¯, which represent porosity and surface roughness, respectively, to be constrained as φ = 0.649 ± 0.023 and �¯ = 16.113° (at 500 μm size scale). This work serves as part of the characterization process for Winchcombe and provides a reference photometry dataset for current and future asteroid missions.

¹Guy Libourel,²Pierre Beck,³Akiko M. Nakamura,⁴Pierre Vernazza,⁵Clement Ganino,¹Patrick Michel
The Planetary Science Journal 4, 123 Open Access Link to Article [DOI 10.3847/PSJ/ace114]
¹Université Côte d’Azur, Lagrange, Observatoire de la Côte d’Azur, CNRS, Nice, France
²UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble, Grenoble, France
³Graduate School of Science, Kobe University, Japan
⁴Université Aix-Marseille, CNRS, Laboratoire d’Astrophysique de Marseille, Marseille, France
⁵Université Côte d’Azur, Géoazur, Observatoire de la Côte d’Azur, CNRS, Valbonne, France

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