A search of outer Trojans on ASTROVIRTEL images

This paper discusses the main results of a search of outer Trojans on ESO/ESA ASTROVIRTEL images, and the usefulness and the limitations of such an archive for the discovery and dynamical classification of minor bodies. The work was performed in the frame of a program having the aim to detect bodies orbiting around the Lagrangian points of the outer planets. A large number of images taken from 1999 to 2001 with the wide field imager (WFI) camera of the 2.2 m telescope of ESO at La Silla for entirely different scientific reasons, but happening to be in the wanted Lagrangian positions, was retrieved with a dedicated search engine. The moving objects present on these images were detected and examined with specific software tools that permitted one to find out about 1500 minor bodies (mostly previously unknown). More than 5000 positions were sent to the Minor Planet Center, and the search was given the designation I03. The total sky area covered by I03 is of approximately 50 square degrees, and in some areas the limiting magnitudes were fainter than the 24th in the R band. A preliminary classification of the kinematics of the I03 discoveries (using a dedicated code, named AMIGO apparent motion interpretation of generic orbits) has produced several Trojan candidates of Jupiter and of the outer planets. Furthermore, pre-discovery positions have been provided for one NEO, three Jupiter Trojans and three TNOs.