| Popis: |
To exploit gravitational lensing for cosmology large, reliable and statistically complete surveys are required. With the Cosmic Lens All-Sky Survey (CLASS) we have set out to achieve these goals. We pre-select targets to be flat spectrum radio sources and map every source with the VLA at 200mas resolution. Candidates having multiple compact components with flux density ratios ≤10:1 and separation in the range 0.3 to 15 arcsec are followed up with high resolution MERLIN and VLBA observations, eliminating those candidates which do not match strictly defined surface brightness and morphological criteria. A complete sample of 11685 sources have been surveyed and nineteen lens systems have been found. |
