This table is an associated to the GRBs Catalog and lists the parameters that define the localization region if the region is a circle. For a given GRB the localization can be provided by different observatories with different region types or by the same region type with different parameters. The different region types reported in literature are the following: circle, annulus, box, dual, annulus intersect, irregular, and intersect. This table contains the description only for the circle region type, the other types are stored in separate tables. The circle region is described by a center given in RA and Dec, and a radius given in degrees. The measurements are reported as found in literature and any differences or remarks are included in one of the table parameter (local_notes). The literature references are provided in the GRBs Catalog main table which is linked to this region table. This table was ingested by the HEASARC in June 2008 based on electronic versions obtained from the author(s), who compiled the catalog in 2005. This is a service provided by NASA HEASARC .