AST-9802732 Helfand Dr. Helfand and Dr. Becker are collaborating to use the FIRST database. The FIRST (Faint Images of the Radio Sky at Twenty-one cm) survey covered 5000 square degrees of the northern sky. The FIRST data are publicly available as are the image database and source catalogs. The FIRST project provides to users a sophisticated catalog search engine and image cutout server. Nearly a quarter of a million hits to the database have been recorded since 1994. The FIRST catalog is now the largest catalog in the NASA Extragalactic Database. The team are undertaking four projects: (1) study of weak gravitational lensing, the angular correlation function, and the angular size-redshift distribution for double radio sources, (2) study of bent double radio sources as tracers, (3) a bright quasar survey along with BL Lacs, red quasars and gravitational lenses, (4) a study of radio stars and rapidly variable radio sources. These projects exploit the sensitivity, morphological fidelity and astrometric accuracy of the FIRST survey. The PI's are adding over 2000 quasars, 300 BL Lacs, and at least 10 lens systems during the course of the project. Bent-double radio galaxies derived from the FIRST survey can be used to select clusters with the efficiency to redshifts of 0.85 and beyond. Since the distorted radio lobes in these systems guarantee that the clusters contain a dense ICM, their sample is critical to understanding the evolution of the x-ray luminosity function in clusters. The PI's are also using the data from the FIRST catalog as a set of background images for which weak lensing effects of the total foreground mass distribution (dark matter plus light) reveals the true nature of large-scale structure on scales of 0.5 to 10 degrees. ***
