const RAY_HARMONICS: readonly [7, 11, 17, 23, 31, 43]
Azimuthal harmonics of the ray pattern, as integer frequencies.
Integers because the pattern has to close: the azimuth is an angle and a non-integer frequency puts a seam along the crater's prime meridian, which draws as one ray that is brighter on one side than the other. Coprime and spread over a decade because a sum of harmonics at nearby frequencies beats rather than looking irregular — these produce a pattern that does not repeat anywhere on the circle.
universe/src/craters.ts:778