  It is difficult to discover pulsars via their gamma-ray emission because
current instruments typically detect fewer than one photon per million
rotations. This creates a significant computing challenge for isolated pulsars,
where the typical parameter search space spans wide ranges in four dimensions.
It is even more demanding when the pulsar is in a binary system, where the
orbital motion introduces several additional unknown parameters. Building on
earlier work by Pletsch & Clark (arXiv:1408.6962), we present optimal methods
for such searches. These can also incorporate external constraints on the
parameter space to be searched, for example, from optical observations of a
presumed binary companion. The solution has two parts. The first is the
construction of optimal search grids in parameter space via a parameter-space
metric, for initial semicoherent searches and subsequent fully coherent
follow-ups. The second is a method to demodulate and detect the periodic
pulsations. These methods have different sensitivity properties than
traditional radio searches for binary pulsars and might unveil new populations
of pulsars.
