Development of the “CAPTIF” Software Facility for the Simulation of Coded Aperture Telescopes and Its Application to “INTEGRAL” and other Instruments

Abstract

To support the development of the next generation of coded aperture telescopes, a software facility has been developed to simulate the response of any mask/detector configuration and the observation of various photon sources, allowing its sensitivity and imaging properties to be evaluated. The system is suitable for any instrument which can be defined by four components: a coded mask, an array of detectors, an identical array of detector collimators and an outer shield. It allows for rotating or alternating masks, for flexibility in the choice of mask/detector shape and for off axis effects inherent in a mask of finite thickness with exponential absorption. Facilities are also provided to simulate point or extended sources and an observation program consisting of a sequence of parameters describing the pointing direction, orientation and exposure of the device. Detector count simulations and image reconstructions have been performed for the evaluation of various designs proposed for the INTEGRAL instruments and for a small, balloon carried coded aperture telescope.