Quote:
Originally Posted by DarkArts
It's your RA axis that aligns to the SCP - that's the only one that matters because you're only counteracting Earth's rotation through the combination of SCP alignment and RA rotation at a rate that's equal and opposite.
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Yes , I thought so .
Quote:
Originally Posted by DarkArts
However, IMHO, the real practical consideration (nothing to do with actually getting SCP alignment) is balancing a heavy weight on a pier. If the pier is tilted, then the weight and lever-arm will create a force due to gravity that may cause more tilt over time.
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I didn't think about that . It's a SW AZEQ6GT + a SW Esprit 150 ED + a SW guide scope + a canon EOS , it's heavy .
Quote:
Originally Posted by DarkArts
The SCP is a projection to a point in space based on the Earth's south pole (the rotational axis). Your SCP alignment stays aligned with the Earth's axis even if the axis itself moves, so you don't need to adjust it.
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Aha , it didn't occur to me that once aligned , no more was needed but now it sounds obvious .
Quote:
Originally Posted by DarkArts
Professional astronomers, star charts, planetarium programs and mount controllers do take these motions into account from what I understand. The epoch setting in a chart or planetarium program, or your mount's handset/controller, is needed for coordinate calculation.
Atmospheric refraction and mount mechanics are probably greater sources of pointing error on any given night. Those, and error in SCP alignment in the first place, are why we have tracking.
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I had no idea , thank you for taking the time to explain to me : )