An Analysis of the Statistics of the Hubble Space Telescope Kuiper Belt Object Search

We calculate statistical limits to the detection of Kuiper belt objects in the Hubble Space Telescope (HST) data of Cochran et al., in which they report the discovery of a population of Halley-sized objects in Pluto-like orbits. Detection of a population of faint objects in these data is limited by the number of false objects that appear owing only to random noise; the number of real objects must exceed the uncertainty in the number of these false objects for the population to be observable. We determine the number of false objects expected owing to random noise in the data of Cochran et al. by measuring the pixel-to-pixel noise level in the raw HST data and propagating this noise through the detection method employed by Cochran et al. We find that the uncertainty in the number of false objects exceeds by 2 orders of magnitude the reported number of objects detected by Cochran et al. The detection of such a population of Halley-sized Kuiper belt objects with these data is therefore not possible.