The recovery as an important part of NEA astrometric follow-up

The number of known near-Earth asteroids (NEAs) has increased rapidly in recent years due to large surveys. This discovery process has to be followed by follow-up observations to obtain a sufficient number of precise astrometric data needed for an accurate orbit determination of newly discovered bodies. Accurate orbit determination requires observations from at least two oppositions. If asteroids are not found in the next apparition, different from the discovery apparition, then they can be considered lost. This is particularly embarrassing for NEAs. If data for different apparitions are not found in the course of precovery surveys or in other archive data, then it is necessary to prepare targeted observations of a particular NEA in the second convenient apparition. Therefore NEA recovery is a very important part of NEA follow-up. We discuss here methods, techniques, and results of planned recoveries at the Klet' Observatory using a 0.57-m telescope equipped with a CCD detector. The Klet' NEA recovery subprogram has brought 21 planned NEA recoveries since 1997, including seven NEAs belonging to the potentially hazardous asteroid category. We briefly mention the overall work on NEA recoveries provided by several NEO follow-up programs as well as the need for communication resources supporting astrometric observers. Finally we present here a planned extension of the Klet' NEA recovery subprogram to fainter objects by means of a new 1.06-m reflector. (C) 2002 Elsevier Science (USA).