Astrometric Study of Two Multiple Stars: ADS 2668 and ADS 8236

Based on CCD observations with the Pulkovo 26-inch refractor in 2003–2018, we have obtained the orbit of the visual double star ADS 2668 AB ( P = 947 yr, a = 2.9″, e = 0.41, ω = 246°, Ω = 131°, i = 114°, T = 1456 yr) for the first time by the apparent motion parameter (AMP) method, which is consistent with the inner orbit of ADS 2668 Aa-Ab, and improved the orbit of ADS 8236 AB ( P = 1996 yr, a = 4.69″, e = 0.39, ω = 201°, Ω = 166°, i = 110°, T = 1246 yr). The inner orbit of the photocenter of ADS 8236 with a period of 4.627 yr has been calculated from the residuals. This orbit of ADS 8236 Ba–Bb supplements the spectroscopic orbit by the elements specifying the orbital plane ( i and Ω ). In both cases, the planes of the inner and outer orbits are noncoplanar. The presence of an additional companion in the system ADS 2668 is discussed.