Herschel Double Star Catalog

I use Herschel Double Star Catalog to indicate a series of published lists of double stars that William Herschel produced in the late 1700s and early 1800s. Designators based on these lists use an H followed by a Roman numeral that indicates the degree of separation-angle. Herschel was particularly interested in double stars as an aid in uncovering proper motion and parallax. James South and William's son John Herschel later reviewed and edited the list.