Planetary and Space Science 56 (2008) 1828–1831 Contribution to the ground-based follow-up of the Gaia space mission R. Teixeira a,Ã , A. Krone-Martins a , A. Milone b , C. Mallamaci c , C. Lo´pez c , J.H. Calderon d , I.H. Bustos Fierro d , M. Fideˆncio a , R. Zalles e , J.L. Muin˜os f , G. Hernandes a , T.E.P. Idiart a , J.E. Horvath a a Instituto de Astronomia, Geofı´sica e Cieˆncias Atmosfe´ricas, Universidade de Sa˜o Paulo, Rua do Mata˜o, 1226, Cidade Universita´ria, 05508-900 Sa˜o Paulo, Brazil b Instituto Nacional de Pesquisas Espaciais, Sa˜o Jose´dos Campos, Brazil c Observatorio Astrono´mico Fe´lix Aguilar, Universidad Nacional de San Juan, Argentina d Observatorio Astrono ´mico, Universidad Nacional de Co´rdoba, Argentina e Observatorio Astrono ´mico Nacional, Tarija, Bolivia f Real Instituto y Observatorio de la Armada, San Fernando, Spain Accepted 5 February 2008 Available online 14 August 2008 Abstract The Gaia Space Mission [Mignard, F., 2005. The three-dimensional universe with Gaia. ESA/SP-576; Perryman, M., 2005. The three- dimensional universe with Gaia. ESA/SP-576] will observe several transient events as supernovae, microlensing, gamma ray bursts and new Solar System objects. The satellite, due to its scanning law, will detect these events but will not be able to monitor them. So, to take these events into consideration and to perform further studies it is necessary to follow them with Earth-based observations. These observations could be efficiently done by a ground-based network of well-equipped telescopes scattered in both hemispheres. Here we focus our attention at the new Solar System objects to be discovered and observed by the Gaia satellite [Mignard, F., 2002. Observations of Solar System objects by Gaia I. Detection of NEOS. Astron. Astrophys. 393, 727] mainly asteroids, NEOs and comets. A dedicated ground-based network of telescopes as proposed by Thuillot [2005. The three-dimensional universe with Gaia. ESA/SP-576] will allow to monitor those events, to avoid losing them and to perform a quick characterization of some physical properties which will be important for the identification of these objects in further measurements by Gaia. We present in this paper, the beginning of the organization of a Latin-American ground-based network of telescopes and observers joining several institutions in Argentina, Bolivia, Brazil and other Latin-American countries aiming to contribute to the follow-up of Gaia science alerts for Solar System objects. r 2008 Elsevier Ltd. All rights reserved. Keywords: Astrometry; Gaia; Solar System; NEOs; Photometry 1. Introduction The Gaia Space Mission will provide a revolutionary astrometric, photometric and spectroscopic database. More than one billion stars will be observed with unprecedented accuracy allowing to discuss many ques- tions concerning the Solar System, the Milky Way and beyond in an extremely solid and never seen base (Mignard, 2005; Perryman, 2005). An important task concerning the Gaia Mission, for the astronomical community, is the ground-based follow-up of science alerts, e.g., the observation from the ground of the large number of transients events to be detected by the satellite: supernovae, microlensing, gamma ray bursts and new Solar System objects. The follow-up of these events is essential to do a better astrophysical characterization and to keep them for further studies. In the case of the Solar System, the transient events corres- pond to the detection by the satellite of a very large number of objects, among them probably more than 10 5 new asteroids (Mignard, 2002; Bayler-Jones, 2004; Thuillot, 2005). ARTICLE IN PRESS www.elsevier.com/locate/pss 0032-0633/$ - see front matter r 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.pss.2008.02.041 Ã Corresponding author. E-mail address: teixeira@astro.iag.usp.br (R. Teixeira).