STF 2579 (Delta Cygni) is not hard to find; it is the brightest star in the northwest wing of the constellation Cygnus, situated approximately 10° west of the star Deneb. The primary component of this system is a blue-white giant of spectral class B9III, which is 2.93 times more massive and has a diameter about 5 times larger than our Sun. The first companion is a yellow-white main-sequence star of spectral class F1V, approximately 1.5 times more massive than the Sun, and is, on average, 157 AU away from the primary component. These two components orbit around their common center of mass approximately once every 657 years, although some sources suggest up to 780 years. A probable third common proper motion (CPM) member of this system is a K-type star with a mass of about 0.7 solar masses. Delta Cygni is expected to become our North Star around the year 11600.

100mm - Resolving components A and B is effortless even at 150x magnification. I observed the primary component as white, and the companion appeared dark orange, almost brown. I am uncertain about the observation of component C; occasionally, there seemed to be a stellar-like flicker in the expected location.