4270ef9b___The_Gamma_Ray_Bursts_Catalog__Definition
[Geometry] Irregular [Definition] 
The 'irregual' region are from the Kippen et al. (1998). This localization region consist of a short thin arc segment derived from a COMPTEL localization combined with an IPN localization where the most likely position corresponds to the maximum obtained from the integral distribution. The COMPTEL localization consists of a circle error region centered at the most likely position within that region.
GRBCAT - The Gamma-Ray Bursts Catalog
Definition