The Effect of Non Gaussian Errors on the Determination of Steeply Falling Spectra

The determination of a steeply falling energy spectrum from rare events with nongaussian measurement errors is a delicate matter. The final shape of the spectrum may be severely distorted as a consequence of non-gaussian tails in the energy resolution of the experiment. We illustrate this effect with the recent experimental efforts to determine the ultra-high energy extreme of the cosmic ray spectrum.