**Planetary ring precession calculator by orbsi.uk**

Calculates the apsidal precession rate of a particle orbiting in the equatorial plane around an oblate planet

Uses this equation (source: Elliot et al 1981 p447 equation 1)

G is the gravitational constant.

M is the mass of the planet.

R is the reference equatorial radius of the planet.

J2 and J4 are the dimensionless terms due to the planet's oblateness.

a is the semimajor axis of the particle orbit.

e is the eccentricity of the particle orbit.

The default parameters which appear at start-up are for Uranus and the midline of its epsilon ring,

source: French et al, in Bergstralh et al 1991 pages 327-409.

This calculator performs only simple validation of input, and therefore relies on the user to input realistic parameter values.