Apparently - "sidereal time" is different to your "observed real time".
eg: If you try to calculate a lunar day length - as observed from Earth - you get a different result than if you calculate it from the surface of the moon.
Something to do with the fact that the surface of the moon is always moving in a different way to your particular part of the surface of the Earth.
This site allows you to calculate your current "sidereal time":
https://www.heavens-above.com/
You will need to input some info (several different ways to do this) to identify which part of the Earths surface you occupy.
Here is another option (but may be pre-programmed for my own location - not certain):
https://www.localsiderealtime.com/#:~:text=6%3A36%3A45
(Maybe just Google: "What is my sidereal time": https://letmegooglethat.com/?q=what+is+my+sidereal+time)
Apparently Sidereal time calculations are critical in programming satellites and rockets/space stations so that they can rendevous or achieve their required orbits.
- Sidereal.png (51.39 KiB) Viewed 267 times