Research Note

Pole and shape of (1459) Magnya, the outer main belt basaltic asteroid^⋆

Observatório Nacional, rua Gal. José Cristino 77, 20921-400 Rio de Janeiro, Brazil
e-mail: jsergio@on.br

Received: 18 April 2015
Accepted: 22 June 2015

Abstract

Context. The basaltic asteroid (1459) Magnya is, to date, the only confirmed example of this kind of asteroid in the outer main belt (Lazzaro et al. 2000). It might be a rare surviving fragment from a larger, differentiated, and subsequently disrupted object most probably unrelated to (4) Vesta.

Aims. We derive the direction of the pole and the shape of asteroid (1459) Magnya in order to increase the knowledge of the body’s physical properties. In particular, these two properties are useful to characterize which regions of the body are being sampled by spectral observations at distinct epochs and telescopes and to better assess the degree of surface homogeneity of (1459) Magnya.

Methods. An observational campaign of (1459) Magnya was set up to determine its pole and shape from photometric lightcurves of the asteroid. These lightcurves were acquired at diverse telescopes and observatories from 2002 to 2014. Additional data from the literature was added, and a method of inversion was applied.

Results. The obtained pole of asteroid (1459) Magnya is given by the ecliptic coordinates λ = 159 ± 10° and β = −75 ± 10°. The asteroid is modeled by a slightly elongated ellipsoid, rotating along the smallest axis with a period of 4.679100 ± 0.000005 h. The derived direction of the pole was used to compute the viewing geometry of the spectroscopic observations of (1459) Magnya obtained by various authors and indicates the necessity of new visible and near-infrared observations in order to correctly assess the degree of homogeneity of its surface.