private float MarsMoon_Magnitude(SkyContext c, int m)
        {
            var r = c.Get(Planet_DistanceFromEarth, Planet.MARS);
            var R = c.Get(Planet_DistanceFromSun, Planet.MARS);

            return(MartianMoons.Magnitude(r, R, m));
        }
        private CrdsRectangular[] MarsMoons_Positions(SkyContext c)
        {
            CrdsHeliocentrical earth = c.Get(Earth_Heliocentrial);
            CrdsHeliocentrical mars  = c.Get(Planet_Heliocentrical, Planet.MARS);

            return(MartianMoons.Positions(c.JulianDay, earth, mars));
        }
        private double MarsMoon_Semidiameter(SkyContext c, int m)
        {
            var distance = c.Get(MarsMoon_Ecliptical, m).Distance;

            return(MartianMoons.Semidiameter(m, distance));
        }