Asteroid models from combined sparse and dense photometric data

¹ Astronomical Institute, Charles University in Prague, V Holešovičkách 2, 18000 Prague, Czech Republic e-mail: [email protected]
² Department of Mathematics and Statistics, Rolf Nevanlinna Institute, PO Box 68, 00014 University of Helsinki, Finland
³ Palmer Divide Observatory, 17995 Bakers Farm Rd., Colorado Springs, CO 80908, USA
⁴ Florida Gulf Coast University, 10501 FGCU Boulevard South, Fort Myers, FL 33965, USA
⁵ Observatoire du Bois de Bardon, 16110 Taponnat, France
⁶ Association T60, 14 avenue Edouard Belin, 31400 Toulouse, France
⁷ 4438 Organ Mesa Loop, Las Cruces, NM 88011, USA
⁸ Observatoire des Engarouines, 84570 Mallemort-du-Comtat, France
⁹ Geneva Observatory, 1290 Sauverny, Switzerland

Received: 16 June 2008
Accepted: 15 October 2008

Abstract

Aims. Shape and spin state are basic physical characteristics of an asteroid. They can be derived from disc-integrated photometry by the lightcurve inversion method. Increasing the number of asteroids with known basic physical properties is necessary to better understand the nature of individual objects as well as for studies of the whole asteroid population.

Methods. We use the lightcurve inversion method to obtain rotation parameters and coarse shape models of selected asteroids. We combine sparse photometric data from the US Naval Observatory with ordinary lightcurves from the Uppsala Asteroid Photometric Catalogue and the Palmer Divide Observatory archive, and show that such combined data sets are in many cases sufficient to derive a model even if neither sparse photometry nor lightcurves can be used alone. Our approach is tested on multiple-apparition lightcurve inversion models and we show that the method produces consistent results.

Results. We present new shape models and spin parameters for 24 asteroids. The shape models are only coarse but describe the global shape characteristics well. The typical error in the pole direction is ~10–20°. For a further 18 asteroids, inversion led to a unique determination of the rotation period but the pole direction was not well constrained. In these cases we give only an estimate of the ecliptic latitude of the pole.