ASTROMETRY OF NEAR-EARTH OBJECTS USING SMALL TELESCOPES

Currently, when a near-Earth object (NEO: any asteroid or comet approa ching the terrestrial orbit about the Sun) is discovered, there is a d istinct chance that it will be lost again due to the lack of suitable follow-up astrometry. The burgeoning international Spaceguard program - which has an aim of discovering and determining the orbits of all po ssible Earth-impactors so that calamitous collisions can be avoided - will make this problem more acute, as the discovery rate increases. Wh en NEOs reach visual magnitudes brighter than 21, they may be observed with suitable CCD-equipped telescopes with apertures of one metre or less; in fact, even 0.25-m aperture instruments are now being employed to great effect in this regard. This means that in the present situat ion, countries or individuals having access to quite modest-sized and modest-priced equipment can make a real, valuable contribution to this international effort. When Spaceguard begins in earnest it will be vi tal that astronomers spread around the world, using small telescopes, take over the tracking of NEOs discovered by the large, expensive, sea rch instruments. The Spaceguard project therefore represents an excell ent opportunity for international collaboration, with scientists in de veloping nations being valuable contributors in a space program with r eal significance for all humankind.