Key points are not available for this paper at this time.
Webster and colleagues reported in 1988 a significant excess of foreground galaxies in the vicinity of quasars. It is shown that if the effect is due to gravitational lensing, then the quasar-galaxy correlation must be smaller than the reported level by a factor ~ 2 and/or the magnitude limit of the survey must be few tenths of a magnitude brighter than the stated limit of BJ_ = 18. 7. Also, contrary to popular belief, the effect does not require that halos of foreground galaxies be composed of microlenses (stars, black holes, etc) ; the quasar-galaxy correlation works equally well with smooth halos. These conclusions follow directly from the quasar luminosity function and are independent of the structure of the lens.
Ramesh Narayan (Sat,) studied this question.