The circular statistic, proposed by Protheore, was extended to be utilized in the field of the particle astronomy. It might be applied to recognition small (n<200) datasets with somewhat higher S/N ratio from those with very low ratio. The statistic was tried for the data-sets obtained by our muon spectrometer (Okayama Muon Telescope). The applicability was well-ascertained, although some problems are left to be solved.
