gfposc can be used to for coordinate searches to find events such as equinoxes and solstices.

gfposc
Abstract
Determine time intervals for which a coordinate of an observer-target position vector satisfies a numerical constraint.

This blueprint action finds geometric conditions of observer-target position coordinates. For instance, it can find the point in time when a coordinate such as range is maximum, minimum, equals, less than, more than, etc. The variety of coordinate systems and coordinate elements (Range, Longitude, etc) give gfposc a wide variety of problems it can solve.