A portrait of 4979 Otawara, target of the Rosetta space mission^*

¹ Astronomical Department of Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italy e-mail: [fornasier; barbieri; lazzarin]@pd.astro.it, bertini@planet.pd.astro.it
² LESIA, Observatoire de Paris, 92195 Meudon Principal Cedex, France e-mail: [antonella.barucci; Mirel.Birlan; Marcello.Fulchignoni; alain.doressoundiram; Nuno.Peixinho]@obspm.fr
³ Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, 02139, USA e-mail: [rpb; asrivkin]@mit.edu
⁴ Institute for Astronomy Hilo, HI 96720, USA e-mail: sjb@ifa.hawaii.edu
⁵ Space Science Institute, 4603 Orange Knoll Ave., La Canada, CA 91011-3364, USA e-mail: harrisaw@colorado.edu
⁶ INAF-Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese (TO), Italy e-mail: dotto@to.astro.it
⁷ INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00040, Monte Porzio Catone (Roma), Italy
⁸ Astronomical Observatory, Adam Mickiewicz University, Sloneczna 36, 60-286 Poznan, Poland e-mail: tmich@amu.edu.pl
⁹ CAAUL, Tapada da Ajuda, 1349-018 Lisboa, Portugal

Corresponding author: S. Fornasier, fornasier@pd.astro.it

Received: 27 May 2002
Accepted: 17 October 2002

Abstract

A physical portrait based on spectral and photometric data of 4979 Otawara, the first asteroid target of the Rosetta mission, is presented. The aim of this work is to investigate the composition of 4979 Otawara and to evaluate its rotation pole orientation. The spectroscopic observations obtained at the Palomar 200´´and IRTF telescopes cover the wavelength range 0.4 to 2.5 μm, and provide a definitive classification of Otawara as an S-type asteroid. An analysis of band depths and slopes places Otawara in the S(IV) subgroup, suggesting a similarity to ordinary chondrite meteorites. Moreover we present new photometric data, obtained at the Asiago Observatory and at the TNG telescope, that allow confirmation of the fast rotational period of hours, and a first indication of the spin vector of Otawara.