How do I set up RA on an equatorial mount telescope
16 September 2003, 11:08 AM
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The manual for my telescope doesn't really make it clear how to set up the RA. I've set the Dec and can manage a polar alignment in order to track but just cannot work out what to do with the RA setting circle so that I can look objects up using their celestial coordinates 
There are two markers on the RA setting circle, one on the top of the RA mount which says RA with an arrow pointing to the numbered circle and a small fixed metal pointer on the side. Which marker do I use? Am I correct in thinking that I should set the RA to the first point of Aries (which rises in Pisces??) and if so, how???
Confused and frustrated
Sal
There are two markers on the RA setting circle, one on the top of the RA mount which says RA with an arrow pointing to the numbered circle and a small fixed metal pointer on the side. Which marker do I use? Am I correct in thinking that I should set the RA to the first point of Aries (which rises in Pisces??) and if so, how???
Confused and frustrated
Sal
16 September 2003, 01:48 PM
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No idea of the practicalities, but you want to arrange it so that an RA of zero is pointing at the first point of Aries. Then you should be able to dial in the RA of the object you want to look at, and it should appear in the viewfinder.
I guess what you want to do is first set up in polar alignment (see here) then rotate in the equatorial plane until you get to the first point of Aries. Then twiddle the RA ring around until zero is pointing in the direction of the scope. Now you should be able to dial in RA coordinates.
I guess what you want to do is first set up in polar alignment (see here) then rotate in the equatorial plane until you get to the first point of Aries. Then twiddle the RA ring around until zero is pointing in the direction of the scope. Now you should be able to dial in RA coordinates.
16 September 2003, 01:59 PM
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OK, I looked at the manual. It says that first you need to do the polar orientation thing.
Then find an object you recognize, point the scope at it then twist the RA ring around until the correct RA is shown (you'll need to refer to a catalogue for this). Now when you move the scope equatorially to track the object you're not actually moving it in RA, so the dial should go round with it. To look at another object, look up its RA in the catalogue, move the little metal pointer to that RA, then swing the scope round until it's lined up with the metal pointer.
Hope this makes sense -- I haven't actually seen the scope in question, but I see it uses a GEM mount. There's a page about GEM mounts here
Then find an object you recognize, point the scope at it then twist the RA ring around until the correct RA is shown (you'll need to refer to a catalogue for this). Now when you move the scope equatorially to track the object you're not actually moving it in RA, so the dial should go round with it. To look at another object, look up its RA in the catalogue, move the little metal pointer to that RA, then swing the scope round until it's lined up with the metal pointer.
Hope this makes sense -- I haven't actually seen the scope in question, but I see it uses a GEM mount. There's a page about GEM mounts here
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