| Nested Test for Point Sources (2007) | |||||||||||||
Abstract | |||||||||||||
| We describe an extension of a test proposed by Lampton for detecting weak and/or short-lived transient point sources in finiteresolution photon-limited maps of the sky. We test the null hypothesis that the count density is spatially uniform (i.e., no point sources) over a limited region of the sky by decomposing that region into a nested set of source regions and background annuli, and testing whether the count density in each source region differs significantly from the count density in each associated background. The tests are by construction independent, so a combined p-value can be rigorously defined. Our aim is to discriminate real point sources from Poisson fluctuations in the background. The maximum-likelihood formalism prescribes a "matched filter" in which the telescope point-spread function is convolved with the sky map. Points on the convolved map that exceed a background-dependent threshold are identified as sources. If the threshold is set properly (and that is straightfo... | |||||||||||||
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