33df54f5_logue_Format___Stellarium_Wiki_Star_Data_Record_Type_1_Description
[Name] b_v [Offset] 68 bits [Type] unsigned int [Size] 7 bits [Description] 
This is the magnitude level in B-V colour. This value refers to one of 256 discrete steps in the magnitude range for the file
Star Catalogue Format - Stellarium Wiki