  The conical Radon transform, which assigns to a given function $f$ on
$\mathbb R^3$ its integrals over conical surfaces, arises in several imaging
techniques, e.g. in astronomy and homeland security, especially when the
so-called Compton cameras are involved. In many practical situations we know
this transform only on a subset of its domain. In these situations, it is a
natural question what we can say about $f$ from partial information. In this
paper, we investigate some uniqueness theorems regarding a conical Radon
transform.
