  Dark matter annihilating in our Galaxy's halo and elsewhere in the universe
is expected to generate a diffuse flux of gamma rays, potentially observable
with next generation satellite-based experiments, such as GLAST. In this
article, we study the signatures of dark matter in the angular distribution of
this radiation, in particular the deterministic ones. Pertaining to the
extragalactic contribution, we discuss the effect of the motion of the solar
system with respect to the cosmological rest frame, and anisotropies due to the
structure of our local universe. For the gamma ray flux from dark matter in our
own Galactic halo, we discuss the effects of the offset position of the solar
system, the Compton-Getting effect, the asphericity of the Milky Way halo, and
the signatures of nearby substructure. We explore the prospects for the
detection of these features by the GLAST satellite and find that, if ~10% or
more of the diffuse gamma ray background observed by EGRET is the result of
dark matter annihilations, then GLAST should be sensitive to anisotropies at
the sub-percent level. Such precision would be sufficient to detect many, if
not all, of the signatures discussed in this paper.

Astrophysics;High Energy Physics - Phenomenology