On Saturday, December 1, 2018 at 2:26:08 PM UTC, Chris L Peterson wrote:
On Sat, 01 Dec 2018 08:34:18 +0100, Paul Schlyter
wrote:

On Fri, 30 Nov 2018 07:15:34 -0700, Chris L Peterson
wrote:
On Fri, 30 Nov 2018 01:36:04 -0800 (PST), StarDust

wrote:

https://www.youtube.com/watch?v=rIesWBTUeiI

It's called Geostationary Oscillation. Not all geo sats are
directly above the equator, they can be slightly inclined whether by
design or insertion failure. The satellite's gyros will compensate
for the movement to keep the footprint centered. Sirius XM sats do a
huge "figure 8" from North to South and back to ensure a uniform
footprint for moving vehicles. A. Kemp - Lockheed Martin
Astronautics?

By definition, all geostationary satellites are above the equator,
and
do not oscillate. If they are inclined, by have a 24 hour orbit,
they
are called geosynchronous, and show that north/south oscillation.

If so, geostationary satellites do not exist since it is impossible
to keep a satellite exactly above the equator at all times. There
will always be some small deviations.

Geostationary satellites exist because they have active systems to
maintain their position. Indeed, once those active systems fail they
do drift out of their geostationary orbit. In most cases,
geostationary satellites nearing the end of their life (or their fuel
supply) are deliberately pushed into a higher orbit in order to free
up valuable and limited space in the geostationary orbital band.

Where are all the nuisances who, for the last 20 years, argue that the Earth's rotation is fixed to stellar circumpolar despite geostationary satellites maintaining a fix on longitude and one sunrise/sunset each 24 hour day ?.

Everyone learned the lesson, at least those who can despite all those fine academic institutions preaching a fiction of more rotations than 24 hour days.