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Imaging high-energy astrophysical sources using Earth occultation (1993)

Zhang, S. N. ; Fishman, G. J. ; Harmon, B. A. ; [et al.]

[s.l.] : Nature Publishing Group

Nature 366 (1993), S. 245-247

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] In visible-wavelength optics, transform imaging has been described for at least the past 30 years12'13, although it has not seen widespread applications. For high-energy astronomy, transform-imaging processes are reviewed by Caroli et al.1 and by Lei et al.14 The coded-aperture ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/366245a0

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Statistical data analysis for gamma-ray astronomy (1990)

Zhang, S. N. ; Ramsden, D.

Springer

Experimental astronomy 1 (1990), S. 145-163

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ISSN: 1572-9508

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract Significance testing, parameter estimation and sensitivity calculations for γ-ray telescopes are discussed for single ‘on-off” astronomical observations. Four widely used significance test methods are examined by Monte-Carlo simulations. The Maximum Likelihood Ratio Method is found to consistently over-estimate the significance of an observation by a few percents whereas the Fisher's Exact Test is shown to be slightly conservative and always under-estimates the significance by about the same amount when the reported significance is about 3σ and therefore it is preferred for γ-ray astronomy applications. Two methods for constructing a confidence interval and an upper limit for γ-ray source counts are discussed. It is found that the method based on the Smooth Transformation provides slightly better estimations. A new formula for the calculation of the sensitivity of a γ-ray telescope is presented, in contrast to the widely accepted one, and their statistical meanings are explained in detail.