The NF/ ranch (where the NF/ Observatory is located) is named after the owners, Bill Neely and his wife, Lori Frasca. When they submitted NF as the cattle brand for the ranch, the New Mexico Branding Board added the slash to the base of the letter F to prevent rustlers from changing the F to an E with a running iron.
The change from NF to NF/ must have worked, since very few cattle have been rustled from the ranch. It has, however, made the name of the Observatory somewhat hard to pronounce for the non-ranching public. The brand is read as ``en eff slash''. We generally skip the slash part and refer to the NF/ Observatory simply as ``en eff oh''.