Spectroscopy of near-Earth asteroids

¹ Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark e-mail: rene@astro.ku.dk
² Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau, Germany e-mail: nathues@linmpi.mpg.de
³ Astronomical Observatory, Box 515, 751 20 Uppsala, Sweden e-mail: Claes-Ingvar.Lagerkvist@astro.uu.se

Received: 15 March 2004
Accepted: 2 November 2005

Abstract

We present spectra and taxonomic classifications of 12 Near-Earth Asteroids (NEAs) and 2 inner Main Belt asteroids. The observations were carried out with the ESO 3.5 m NTT and the Danish 1.54 m telescope at La Silla, Chile. Eleven of the investigated NEAs belong to the S class while only one C-type has been identified. Two NEAs were observed at phase angles larger than  introducing significant phase reddening. In order to allow for comparisons between spectra of asteroids observed at different phase angles we make attempts to correct for this effect. However, it turned out that a uniform approach based on previous measurements of phase reddening by means of observational data is not reasonable. For the NEAs we question the approach of taxonomic classification in terms of subgroups, when the classification is based on spectra obtained at large phase angles.