Various Orbital Solutions and Double Star Statistics

For the past twenty years, the primary double star observational technique utilized at the US Naval Observatory (USNO) has been speckle interferometry. Our two speckle cameras have been used on a variety of telescopes: our 26-inch in Washington, the Naval Observatory Flagstaff Station (NOFS) 61-inch, the McDonald Observatory 82-inch, the Mt. Wilson Observatory 100-inch and the twin 4 meter telescopes of Kitt Peak National Observatory (KPNO) and Cerro Tololo Interamerican Observatory (CTIO). While these instruments have each yielded many observations, they have been involved in rather different programs, with the 26-inch observing primarily the so-called “neglected" pairs and larger instruments conducting duplicity surveys and observing close, astrophysically interesting systems. Although speckle is quite successful at resolving relatively close pairs, for those pairs which are both bright and very close long baseline optical interferometry may be the only option. Utilizing both the Center for High Angular Resolution Astronomy (CHARA) Array and the Navy Optical Interferometer (NOI), numerous hard-to-observe pairs first resolved by speckle have been observed using these arrays’ superior resolution capabilities; this has allowed their orbits to be significantly improved; examples of pairs observed by each of these instruments are presented. At the other separation extreme, a cache of photographic plates taken with the USNO double star camera has been digitized and processed. Some 66 plates of Sirius A and B taken between 1970 and 1984 have been reduced, which represents a 10% increase in the total number of published measures enabling a significant improvement over the current “best" Sirius orbit, almost one full revolution later. Also presented are systems whose most recent solutions significantly contradict earlier ones and should serve as a warning to those who seek to compute solutions as soon as possible and also to those who might assume that just having a solution closes the book on a pair. In addition to providing a summary of the current double star observing done by the USNO, statistics of the double star catalogs are presented.