f1 = r1 = x1 (event; perhaps: spacetime coordinates) is an equinox for season x2 at location/of or for celestial body/object d3 = x3 with respect to orbit/sun x4.
x2 is inserted in order to maintain parallel structure to that of "3 = x3 with respect to orbit/sun x4.">dornilteikezraifau" (although note that this one is a season and that one can be a property abstraction; see the notes for that word) and cannot be derived from the relevant veljvo. Use of/reference to a season via seltau is, of course, also acceptable. Use "critoinsa" etc. for some amount of neutrality and objectivity concerning location and any biases which may be at play therefor. See also: "ctenilteikeznulfau".