Position angle a hypothetical binary star with a PA of 135 degrees, that means an imaginary line in the eyepiece drawn from the north celestial pole to the primary (P) would be offset from the secondary (S) such that the NCP-P-S angle would be 135 degrees. When graphing visual binary orbits, the NCP line is traditionally drawn downward—that is, with north at bottom—and PA is measured counterclockwise. Also the direction of the proper motion can for example be given by its position angle. The definition of position angle is also applied to extended objects like galaxies, where it refers to the angle
The Octagon House was occupied by 10 families, probably one living in each room, tenement-apartment-style. The residents were probably mostly workers in the factories that populated Foggy Bottom. In 1898, the American Institute of Architects (AIA) selected the Octagon to be their new national headquarters. They rented the building for 4 years, and then purchased it outright in 1902. The Octagon would continue to serve as AIA's headquarters until the construction of the current headquarters building in the 1960s. The Octagon opened as a museum in 1970. The museum was restored to its 1817–18 era appearance in the early 1990s—the wall colors and