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Pier/mount angle

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#1 Dr Morbius

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Posted 12 October 2012 - 03:35 PM

Hi,
I seem to be having a problem with my angles, and am getting conflicting reports. The problem is I have a Meade fixed (solid) steel pier for my 16 inch LX-200 scope, and the pier is set for 41 Degrees (no adjustments)which is for Long Island, NY. I will be moving the whole kit and kaboodle to New Mexico, which is 34 degrees in latitude. I'm having a machine shop make the adjustment but he wants to know where do you start your zero degree mark? Is zero degrees from the level as in horizontal, or vertical? In other words, does he add 7 degrees to the 41 degrees or subtract the 7 degrees? Right now, if I'm standing with the pier in front of me and I laid a rocket on it the fins would be lower than the nose cone so when I fired it up it would shoot up towards the sky at 41 degrees. If it was cut and welded at 34 degrees and the same rocket was lit, would it go not quite as high and as far?

Hope this is making some sort of sense, cause the owner of an astronomy shop said to cut out a piece of the pier to lower the angle of it - and yet the machine shop owner said if your moving south you have to add a piece to raise the angle. UUUGHH!
Thanks for any and all replies.

Steve :question:

#2 Mirzam

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Posted 12 October 2012 - 04:12 PM

Steve,

Assuming that I am visualizing your pier correctly, (a photo would be helpful), you want the top plate of the pier to be angled to point to the celestial north pole. Like Polaris, the north pole appears lower in the sky as you move to more southerly locations. This means that your NM pier will have a "flatter" angle by 6 degrees. If you were set up on the equator it the pier plate would be horizontal.

JimC

#3 Mirzam

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Posted 12 October 2012 - 04:21 PM

Now thinking further it depends on how your scope bolts to the plate. If you have a fork mount that bolts directly to the pier plate we are talking about, it may be that the plate does indeed need to be steeper, not shallower.

The right ascension axis of the fork mount, which passes up from the base through the center of the fork is what needs to be aligned with the celestial pole. The mounting surface itself would be at a steeper angle (6 degree steeper).

Again a picture would be a good idea.

JimC

#4 gavinm

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Posted 13 October 2012 - 12:19 AM

latitude is simply the angle to measured from the centre of the Earth - equator = zero degrees. Your RA axis needs to point at the celestial pole which is the same as your latitude. So at the equator, thats 0 degrees. ie an equatorial mount needs to be horizontal to the ground/horizon. The closer to the equator you move, the more "horizontal" your RA needs to be.

So going from 41 - 34 degrees, your RA needs to be more horizontal/flatter - you need to decrease the angle of your pier. The extra 7 degrees needs to be removed. To do this, you need to cut out a section. EDIT: depending on what side they are removing, of course...

To answer your question, the angle of your pier is measured from horizontal.

The pier plate itself (which is perpendicular to the RA axis) will be steeper/more vertical/more angle.

Draw them a picture - the terminology can get very confusing.

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#5 gavinm

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Posted 13 October 2012 - 12:47 AM

Sorry, for the quick drawing - i should have labelled the angle for you. Obviously its the angle of the top tube measured from horizontal. The pier plate (the end of the tube) is perpendicular to this angle.

#6 PGW Steve

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Posted 13 October 2012 - 12:58 AM

Excellent drawing Gavin!!!

#7 Dr Morbius

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Posted 14 October 2012 - 11:02 PM

Gavin, by jove you've done it! Thank you very much!!!

Steve






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