Accurate FASTT positions and magnitudes of asteroids: 1997-1999 observations

This paper presents 56,256 positions of 1940 asteroids determined in 1997-1 999. The CCD observations were taken with the Flagstaff Astrometric Scannin g Transit Telescope (FASTT) and were reduced differentially to ICRF equator ial positions using reference stars taken from the ACT star catalog. Accura cies of +/-0 " .06 were achieved in each coordinate for well-exposed images which degrade to about +/-0 " .20 for the faintest asteroids observed (V s imilar to 17.5). Similarly, magnitudes were determined with accuracies rang ing from +/-0.03 to +/-0.11 mag. These observations provide a large databas e of accurate and homogeneously determined positions and magnitudes for mos t of the first 2000 numbered asteroids and other specially selected objects which can be used to calculate dynamical masses for asteroids, support spa cecraft missions such as Near Earth Asteroid Rendezvous and Deep Space 1, s ignificantly improve the accuracies of occultation predictions, and by usin g the photometry, investigate the shapes, binary statuses, precessions, and opposition effects for a large number of asteroids. This is an ongoing obs ervational project, and some early results are reported. In particular, ast eroids with diameters smaller than 75 km appear to be more irregular in sha pe than their larger counterparts.