The sensitivity of coded mask telescopes

Abstract

Simple formulae are often used to estimate the sensitivity of coded mask X-ray or gamma-ray telescopes, but these are strictly only applicable if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given which allows the calculation of the sensitivity. We consider certain aspects of the optimization of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels.

To be published in "Applied Optics"

References in corpus (7)

• The Burst Alert Telescope (BAT) on the Swift MIDEX Mission
• First Results from the All-Sky Monitor on the Rossi X-ray Timing Explorer
• The Swift/BAT High Latitude Survey: First Results
• The Spiros imaging software for the Integral SPI spectrometer
• Optimizing wide-field coded aperture imaging: radial mask holes and scanning
• EXIST's Gamma-Ray Burst Sensitivity
• A Fourier-Based Algorithm for Modelling Aberrations in HETE-2's Imaging System

Cited by in corpus (16)

• The 22-Month Swift-BAT All-Sky Hard X-ray Survey
• The deep look onto the hard X-ray sky: The Swift - INTEGRAL X-ray (SIX) survey
• Coded Aperture Imaging in High-Energy Astrophysics
• Analysis of extremely low signal-to-noise ratio data from INTEGRAL/PICsIT
• A Combined Compton and Coded-aperture Telescope for Medium-energy Gamma-ray Astrophysics
• The LOFT Wide Field Monitor
• Harvesting BAT-GUANO with NITRATES (Non-Imaging Transient Reconstruction And TEmporal Search): Detecting and localizing the faintest GRBs with a likelihood framework
• Searching for the 511 keV annihilation line from galactic compact objects with the IBIS gamma ray telescope
• Imaging Analysis of the Hard X-ray Telescope ProtoEXIST2 and New Techniques for High Resolution Coded Aperture Telescopes
• The design of the wide field monitor for LOFT
• Telescope Concepts in Gamma-Ray Astronomy
• Coded Mask Instruments for Gamma-Ray Astronomy
• How Distance Affects GRB Prompt Emission Measurements
• Simulations of a 2 x 1.5D coded aperture camera for X-ray astronomy
• Imaging effects due to pixel distortions in CdZnTe (CZT) detectors -- results from the HREXI Calibration Facility (HCF)
• In-flight calibration of the INTEGRAL/IBIS mask