<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.social/@eggrobin" class="u-url mention">@<span>eggrobin</span></a></span> my guess is this is VSOP87 or a newer model of the same ilk. it's used to calculate the position of the sun in the sky at a given time using a series of summed periodic functions to correct for the multibody gravitational forces that lead to variations from the nominal (Kepler) orbital paths. my wife's been doing similar things for the magellanic clusters in astropy recently.</p>
