A search for gravitational lensing among highly luminous quasars - Observational strategy and survey

The observational techniques employed to search for gravitational lensing effects in highly luminous quasars (HLQs) are given, along with results of the observations. The program, begun in 1986, considers the visible and dark matter distributions at different scales in the universe to determine which extragalactic objects are gravitationally lensed. The Hubble parameter and galaxy masses are determined from the observations, and observations of microlensing effects provide data on HLQ size and structures. The redshifts are found to be between 1 and 3.6, with apparent visual magnitudes 16-18.5 and absolute visual magnitudes between -29 and -30.6. About one quarter of the images exhibit either multiple components, elongated structures, jetlike features, or faint nearby galaxies. The double quasar UM 673 and its 'overlying' lens galaxy is given as a prime example of an HLQ that is gravitationally lensed. It is theorized many more HLQs are gravitationally lensed, and specific future observations are recommended.