The 1977 Palomar-Leiden Trojan survey

The 1977 Trojan campaign, consisting of 68 plates taken in October 1977 with a 122-cm Schmidt telescope, is reviewed. A total of 26 Trojan asteroids were found, together with five Hungaria-type asteroids and only one Hilda-type asteroid. The accuracy of the orbital elements derived from a 15- or 14-days arc is found to be comparable to first-class orbits in the Palomar-Leiden Survey (PLS) (van Houten et al., 1970); the orbits presently derived from a 10- or 11-days arc are considerably better than the third class PLS orbits, which are based on a 9-days arc. Because the limiting magnitude of the asteroids found is practically the same for the PLS and the present survey, the number of Trojans found is complete down to a photographic magnitude of 20.