4270ef9b___The_Gamma_Ray_Bursts_Catalog__Definition
[Geometry] Annulus Intersection [Definition] 
This localization region consists of in the intersection up to three annuli. Each annulus is described by a center given in RA and Dec, the radius of the annulus and by the half-width of the annulus.
GRBCAT - The Gamma-Ray Bursts Catalog
Definition