General results on equatorial geodesics are exposed in the case of circular spacetimes featuring an equatorial reflection symmetry. The way the geodesic equation equivalently rewrites in terms of an effective potential is explicitly recalled for circular and non-circular equatorial geodesics. This provides a practical tool to discuss their stability. Statements are illustrated in Kerr spacetime.

中文翻译：

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关于圆形时空赤道测地线的注记

在具有赤道反射对称性的圆形时空的情况下，公开了赤道测地线的一般结果。对于圆形和非圆形赤道测地线，测地线方程等效地重写为有效势的方式被明确地召回。这提供了一个实用的工具来讨论它们的稳定性。声明在克尔时空中说明。