Understanding Tracking

[Star-Gazer]

Hi

As a total newbie I am trying to get information to explain tracking to me and I am struggling to find anything. I want to know what sidereal, lunar etc tracking is and I keep coming up blank from the net. can anyone enlighten me please or point me to some sites?

ta

[lukebl]

Sidereal tracking compensates for the earth's rotation, so it follows the stars (if it's aligned correctly) and stops them moving out of the field of view of the telescope.

Lunar tracking follows the moon, which moves across the sky at a different rate to the rest of the stars.

Then there is solar tracking which, as the name implies, tracks the sun which also moves across the sky at a different rate to the stars or the moon.

[MartinB]

This is my simple understanding that serves me well. I'm sure there are some on the forum who would define it more precisely complicatedly!

Sidereal time is time as marked by movement of the stars caused by the earths rotation. 24 sidereal hours is very close to but not exactly 1 day. To track stars your mount needs to track at sidereal rate.

The moon moves across the sky more slowly than the stars which is easily seen when looking at the moon against the stars from one night to the next. It takes roughly 29 days for the moon to return to the same position against the stars - a lunar month.

So the lunar tracking rate is a bit slower than sidereal. You can track the moon ok with sidereal but will have to make the odd tweak to get it back fully in the fov.

That is my simplistic understanding anyway.

[MartinB]

Sorry, Luke posted as I was typing

[Star-Gazer]

I'm not being funny but this much I knew already!!

What I am after is much more detail. I need to know the math involved as well as I intend to study accuracy of goto systems and tracking capabilities.

Also anyone who uses the az goto synscan system and knows about lunar rate because I set the time and position last night but did not do any alignment - as per the manual - and set it to lunar tracking and the moon kept disappearing from my ep!

ta

[JKB]

Diurnal motion - Wikipedia, the free encyclopedia Diurnal motion might explain a bit more?

[Stephen]

I'm not being funny but this much I knew already!!

What I am after is much more detail. I need to know the math involved as well as I intend to study accuracy of goto systems and tracking capabilities.

Also anyone who uses the az goto synscan system and knows about lunar rate because I set the time and position last night but did not do any alignment - as per the manual - and set it to lunar tracking and the moon kept disappearing from my ep!

ta

If you're not aligned, it's not going to track - no?

[Star-Gazer]

This is one of the reasons I am asking because I read the manual to say that you don't need to align the system to track - just put in the position and time at least. I did this and it didn't seem to work.

edit - just checked and I made an error - I used tracking and not auto-tracking and this was the problem. If using auto-tracking you don't need to align according to the manual and just have to enter the time and positon.

Thanks for diurnal I will look it up now.

Thanks for all the responses.

ta

[Star-Gazer]

Can anyone tell me howcome the tracking option on the mount has three choices (lunar, sidereal, and solar) but the auto tracking only has one option "autotrack". How does it know I want to track the moon for example and not the stars or is it just for stars?

[Stephen]

Removed