[JumpCrisscross]

The IERS reference median is “the weighted average (in the least squares sense) of the reference meridians of the hundreds of ground stations contributing to the IERS network” [1].

[1] https://en.m.wikipedia.org/wiki/IERS_Reference_Meridian

[moffkalast]

Ah so it's just averaged out, that's a decent solution I suppose. But that still makes it fixed to the surface for the most part.

[JumpCrisscross]

> still makes it fixed to the surface for the most part

Which makes sense. That’s what we’re trying to measure. You could fix it to a point on the core’s surface, but what wouldn’t be practically useful.