Notes. The parameters x₀, y₀, υx₀, and υy₀ describe the location and motion of the mass in the coordinate system of the AO data in RA and Dec. Because GRAVITY directly measures the separation vector, we do not need to include such coordinate system offsets for the GRAVITY data. The third velocity υz₀ is the offset of the motion in the radial direction along the line of sight, the negative sign means a blueshift or a motion toward the observer. The parameters (a, e, i, Ω, ω, t_peri) are the classical orbital elements semimajor axis, eccentricity, inclination, position angle of ascending node, longitude of pericenter, and the epoch of pericenter passage. The orbital elements are defined as the osculating orbital elements at t = 2010.0, i.e., the conversion to position and velocity is done at that epoch assuming a Kepler orbit.