[jheriko]

thats a fair cop

tbh the small error can be very easily fixed. its close to the difference between a sine wave and its linear piecewise approximation from tip to tip, hence the very high accuracy on the quarters

you could go even further and remove the error from path being nearly a precessing ellipse...

in both cases what you will get is nothing that you would detect by eye or even with a telescope.

for the stated purpose this algorithm does fine in almost every use case including astronomical ones.