  As an extension of the ideas of Hanbury-Brown and Twiss, a method is proposed
to eliminate the phase noise of white chaotic light in the regime where it is
dominant, and to measure the much smaller Poisson fluctuations from which the
incoming flux can be reconstructed (via the equality between variance and
mean). The best effect is achieved when the timing resolution is finer than the
inverse bandwidth of the spectral filter. There may be applications to radio
astronomy at the phase noise dominated frequencies of $1 - 10$GHz, in terms of
potentially increasing the sensitivity of telescopes by an order of magnitude.
