  The quantum Fisher information (FI), when applied to the estimation of the
separation of two point sources, has been shown to be non-zero in cases where
the coherence between the sources are known. Although it has been claimed that
ignorance of the coherence causes the quantum FI to vanish (a resurgence of
Rayleigh's curse), a more complete analysis including both the magnitude and
phase of the coherence parameter is given here. Partial ignorance of the
coherence is shown to potentially break Rayleigh's curse, whereas complete
ignorance guarantees its resurgence.
