  In our recent paper (Yadav et al. 2007) we described a fast cubic
(bispectrum) estimator of the amplitude of primordial non-Gaussianity of local
type, f_{NL}, from a combined analysis of the Cosmic Microwave Background (CMB)
temperature and E-polarization observations. In this paper we generalize the
estimator to deal with a partial sky coverage as well as inhomogeneous noise.
Our generalized estimator is still computationally efficient, scaling as
O(N^3/2) compared to the O(N^5/2) scaling of the brute force bispectrum
calculation for sky maps with N pixels. Upcoming CMB experiments are expected
to yield high-sensitivity temperature and E-polarization data. Our generalized
estimator will allow us to optimally utilize the combined CMB temperature and
E-polarization information from these realistic experiments, and to constrain
primordial non-Gaussianity.
