  We compare the field-field g(1)(\tau), intensity-field g(3/2)(\tau), and
intensity-intensity g(2)(\tau) correlation functions for models that are of
relevance in astrophysics. We obtain expressions for the general case of a
chaotic radiation, where the amplitude is Rician based on a model with an
ensemble of harmonic oscillators in Brownian motion. We obtain the signal to
noise ratios for two methods of measurement. The intensity-field correlation
function signal to noise ratio scales with the first power of |g(1)(\tau)|.
This is in contrast with the well-established result of g(2)(\tau) which goes
as the square of |g(1)(\tau)|.
