Analysis of the Orbital Elements of Binary Black Hole in the Quasar 3C380

Binary black holes (BBHs) are considered to be at a stage of massive black hole (MBH) formation in active galactic nuclei (AGNs). The orbital motion of BBHs produces relativistic aberration of the jets emanating from an AGN. This relativistic aberration causes a helical structure in jets, and analysis of the helical structure can determine BBH orbital parameters. The superluminal quasar 3C 380 exhibits a helical jet structure that may be caused by the orbital motion of BBHs. We attempt to determine the orbital elements by analyzing the structure and motion of the jets in 3C 380 from multi-epoch VSOP and VLBA images at 4.8 GHz. We compare the images with jet models that were calculated based on BBH orbits with various parameters, and determine the best-fit orbital elements.