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Mount leveling through star alignment

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#1 tomo

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Posted 23 July 2010 - 09:10 AM

I'm sure everyone is familiar with the great WebCamScheinern application and other software apps that greatly help polar alignment. This got me thinking - does anyone know of a technique of using the telescope to sight stars which can check the mount level.

Yes, I know it is not important for PA other than the first goto slew, and that it only really applies to permenant piers, but I'm very anal and the depth of knowledge on CN never ceases to amaze me.

I'm thinking that a set of four stars (two with the same RA and two with the same DEC) should do it.

Any thoughts?

Clear skies, Tommy

#2 jrcrilly

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Posted 23 July 2010 - 10:00 AM

I'm thinking that a set of four stars (two with the same RA and two with the same DEC) should do it.


No; RA and DEC are relative to the celestial poles. An EQ mounted telescope has no way of knowing what its mounting arangements are relative to anything else. The concept of "level" simply doesn't enter into it. If, for some reason, you want to align the mount's base relative to the horizon (level) you'll have to measure that relative to the horizon.

#3 tomo

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Posted 23 July 2010 - 10:14 AM

Thanks for the input. So level has no effect what-so-ever, even on original "first-star" slew? So if I have good PA (+/- 2 mins or less) then I should get that star in the center of FOV everytime? Thanks for your patience as I try to wrap my head around these concepts.

#4 jrcrilly

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Posted 23 July 2010 - 10:46 AM

So level has no effect what-so-ever, even on original "first-star" slew?


Yes, that's right.

So if I have good PA (+/- 2 mins or less) then I should get that star in the center of FOV everytime?


Probably not with that mount. There are many variables that do affect the first alignment star slew. Among them are (1) how close the initial mount orientation (home position) is to that which the mount expects, (2) the accuracy of the time and location data input to the computer, (3) the precision of the encoders and drives, (4) the orthogonality of the mount and optical tube.

#5 tomo

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Posted 23 July 2010 - 11:30 AM

Thanks John. Like I said, I'm in awe of the knowledge of the people on CN.

Cheers, Tommy

#6 tomo

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Posted 23 July 2010 - 11:33 AM

So the only thing that leveling is good for is to keep the ALT/AZ adjustments independent when doing PA, thereby reducing iterations.

#7 jrcrilly

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Posted 23 July 2010 - 12:00 PM

So the only thing that leveling is good for is to keep the ALT/AZ adjustments independent when doing PA, thereby reducing iterations.


Precisely! :waytogo:






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