More than 160 near Earth asteroids observed in the EURONEAR network ^*,**

¹ IMCCE, Observatoire de Paris, 77 avenue Denfert-Rochereau, 75014 Paris Cedex, France e-mail: mirel.birlan@imcce.fr
² Isaac Newton Group of Telescopes, La Palma, Canary Islands, Spain
³ Instituto de Astronomía, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
⁴ University of Bucharest, Department of Physics, Platforma Mǎgurele, Str. Fizicienilor nr. 1, CP Mg - 11, Bucharest-Magurele 76900, Romania
⁵ Institute for Space Sciences, Bucharest - Magurele 077125, Romania
⁶ Astronomical Observatory “Admiral Vasile Urseanu”, Bd. Lascǎr Catargiu, nr. 21, sect. 1, Bucharest, Romania
⁷ The Astronomical Institute of the Romanian Academy, Str. Cuţitul de Argint 5, 040557 Bucharest, Romania
⁸ Astronomical Institute, Academy of Sciences of the Czech Republic Fricova 1, 25165 Ondrejov, Czech Republic
⁹ Modra Observatory, Department of Astronomy, Physics of the Earth and Meteorology, FMFI UK, Bratislava 84248, Slovakia
¹⁰ The Romanian Society for Meteors and Astronomy (SARM), Târgovişte, Romania
¹¹ Rheinische-Friedrich-Wilhelms Universitaet Bonn Argelander Institut fuer Astronomie Regina-Pacis-Weg 3, 53113 Bonn, Germany
¹² Babes-Bolyai University, Faculty of Mathematics and Informatics, Str. Mihail Kogǎlniceanu nr. 1, 400084 Cluj-Napoca, Romania
¹³ Astroclubul Bucureşti, Bd. Lascǎr Catargiu, nr. 21, sect. 1, Bucharest, Romania
¹⁴ Armagh Observatory, College Hill, Armagh BT61 9DG, UK
¹⁵ Departamento de Ingeniería de Sistemas y Computación, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
¹⁶ Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Finland

Received: 10 July 2009
Accepted: 16 November 2009

Abstract

Context. The EUROpean Near Earth Asteroid Research (EURONEAR) is a network which envisions to bring some European contributions into the general context traced by the Spaceguard Foundation which was carried out during the last 15 years mainly by the US with some modest European and amateur contributions.

Aims. The number of known near Earth asteroids (NEAs) and potentially hazardous asteroids (PHAs) has increased tremendously, mainly thanks to five major surveys all focused on the discovery of new bodies. But also other facilities are required to follow-up and improvement the orbital parameters and to study the physical properties of the known bodies. These goals are better achieved by a co-ordinated network such as EURONEAR.

Methods. Astrometry is mandatory in order to acquire the positional information necessary to define and improve orbits of NEAs and PHAs and to study their trajectories through the solar system, especially in the vicinity of Earth. Photometry is required to derive some physical information about NEAs and PHAs. In order to achieve these objectives, the main method of research of the EURONEAR is the follow-up programme of objects selected by a few criteria, carried out mostly at 1 m-class telescopes endowed with medium and large field cameras.

Results. 162 NEAs summing more than 1500 individual positions were observed for a total time of 55 nights in both visiting mode and regular runs using nine telescopes located in four countries. The observations were reduced promptly and reported to the Minor Planet Centre (MPC) which validated and included them in the MPC and NEODyS databases following the improvement of their orbital elements. For one binary NEA we acquired photometry and were able to determine its orbital and rotational periods. Complementary to the follow-up work, as many as 500 unknown moving objects consistent with new Main Belt asteroids and one possible NEA were discovered in the analyzed fields.

Conclusions. Our positions present 1 precision with an accuracy of 0.2–0.4, sufficient for achieving our immediate main goals. The observations and data reduction were conducted by our network members, which included some students and amateurs supervised by professional astronomers. In most cases, we increased the observational arcs decreasing the uncertainties in the orbits, while in some cases the new positions allowed us to recover some bodies endangered to be lost, defining their orbits.