Population and size distribution of small Jovian Trojan asteroids

We present a study of Jovian Trojan objects detected serendipitously during the course of a sky survey conducted at the University of Hawaii 2.2 m tel escope. We used a 8192 x 8192 pixel charge-coupled device (CCD) mosaic to o bserve 20 deg(2) at locations spread over the L4 Lagrangian swarm and reach ed a limiting magnitude V = 22.5 (50% of maximum detection efficiency). Nin ety-three Jovian Trojans were detected with radii 2 km less than or equal t o r less than or equal to 20 km (assumed visual albedo 0.04). Their differe ntial magnitude distribution has a slope of 0.40 +/- 0.05, corresponding to a power-law size distribution index 3.0 +/- 0.3 (1 sigma). The total numbe r of L4 Trojans with radii greater than or equal to 1 km is of order 1.6 x 10(5), and their combined mass (dominated by the largest objects) is simila r to 10(-4) M-Earth. The bias-corrected mean inclination is 13.degrees 7 +/ - 0.degrees 5. We also discuss the size and spatial distribution of the L4 swarm.