For a given family of orbits f(x, y) = c which can be traced by a mat
erial point of unit in an inertial frame it is known that all potentia
ls V(x, y) giving rise to this family satisfy a homogeneous, linear in
V(x, y), second order partial differential equation (Bozis, 1984). Th
e present paper offers an analogous equation in a synodic system Oxy,
rotating with angular velocity omega. The new equation, which relates
the synodic potential function Omega(x, y) = -V(x, y) + 1/2 omega(2)(x
(2) + y(2)) to the given family f(x, y) = c, is again of the second o
rder in Omega(x, y) but nonlinear. As an application, some simple comp
atible pairs of functions Omega(x, y) and f(x, y) are found, for appro
priate values of omega, by adequately determining coefficients both in
Omega and f.