  We study the asymptotic behaviour of needlets-based approximate maximum
likelihood estimators for the spectral parameters of Gaussian and isotropic
spherical random fields. We prove consistency and asymptotic Gaussianity, in
the high-frequency limit, thus generalizing earlier results by Durastanti et
al. (2011) based upon standard Fourier analysis on the sphere. The asymptotic
results are then illustrated by an extensive Monte Carlo study.
