A few brief notes on the equivalence of two expressions for statistical significance in point source detections

08/12/2020

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by   James Theiler, et al.

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The problem of point source detection in Poisson-limited count maps has been addressed by two recent papers [M. Lampton, ApJ 436, 784 (1994); D. E. Alexandreas, et al., Nucl. Instr. Meth. Phys. Res. A 328, 570 (1993)]. Both papers consider the problem of determining whether there are significantly more counts in a source region than would be expected given the number of counts observed in a background region. The arguments in the two papers are quite different (one takes a Bayesian point of view and the other does not), and the suggested formulas for computing p-values appear to be different as well. It is shown here that the expressions provided by the authors of these two articles are in fact equivalent.