Any serious attempt to establish the value of low energy γ-ray astronomy as an observational science must ensure that new telescopes are capable of detecting a significant number of celestial sources. Furthermore, the instruments should combine the high sensitivity with a fine angular resolution imaging capability. Since it is impossible to focus γ-ray photons, the only way to manipulate them is to cast a shadow onto a suitable detector. A single pinhole, in an opaque material, above a position sensitive detector, will cast an image of the sky onto this plane. However, the small effective aperture of a pinhole leads to a very low sensitivity instrument and, since γ-ray telescopes are constrained to operate in a regime of low signal to noise, a larger aperture is required. The optimum solution under these conditions, is to construct the absorbing mask from an array of pinholes, such that the open fraction is one half. This is the principle of the coded aperture mask technique. In this paper we describe a telescope, for operation on a dedicated spacecraft, which has the capability of locating point sources of "Y -radiation with a precision of one or two arc minutes. The sensitivity of this instrument which operates over the range 10 keV - 3 MeV, is such that, for observations lasting one day, one will be able to detect sources having an intensity of lx10uph cm`keV1. With this sensitivity at least 1000 sources should be accessible during the two year observing period.