I am in the process of building an observatory and have a few basic questions.
1. How far 'up' into the dome should the telescope sit? Should the end of the scope just clear the inside edge, sit below the bottom edge, or where in the middle? Is there a technical reason for placement or is it mostly based on aesthetics and peripheral design considerations?
2. Given a polar mounted scope, should the center of the pier be exactly in the center of the dome or should the optical zenith be the exact center? Does the 6"-8" difference really matter in the long run?
3. I am building the observatory as an adjunct to a larger barn. The rational is complex but non-negotiable. The observatory will be on the south side which will limit my north viewing to a minimun angle of ~35degrees. At 39degrees NLat, I should still be able to see Polaris for scope alignment. Does anyone see a problem in that?

Finally, if someone could share how one posts images, I'd be happy to upload drawings for comments.
Thanks!

Haze!
Welcome to Xosmos!
Since I had posted the whole series of operations to post images here before, I just spent 15 minutes poking around and found the post on that issue.

Sooooo...

I copied that post (it was in planetariums) to the "Global Announcements" section for all to find and use. Enjoy!

But you had other questions...
- Location in the dome, to taste or to specs?
- Center the pier or offset?
- Barn almost blocks Polaris, bad?

You have only 2 considerations on scope-in-the-dome geometry:
1. How far down to the horizon do you want to reach?
2. Will I bonk my head when I look through the scope (for Newt owners)
2. Will I hit my scope on the dome cause it's so darn long (for refractors)
2. Will he ever reach #3?

So, it's a matter of taste. The views near the horizon can be yucky, but, sometimes you DO want to have a look there... Lots of time you can't even SEE the horizon for trees, houses and such (barns?) blocking your view...
Center the pier? If you have a fork mounted Schmidtt Cassegrain with a wedge, then it might be best to do a little Southward offset. You would have the center of the declination axis centered...
Barn blocking Polaris? Not too bad, in fact you could use the barn roof to guide you to it! It's always in (approx) the same spot, so if it's always just to the left of the cupola, or directly above the barn door, or next to the peak of the barn roof, then it's easy to find. Besides, with an observatory, you only need to find Polaris once! After you're aligned, you don't need to find it again! Cool, huh?
Rich 8)

For the pier offset:

Wedge mounted - Offset the pier (or top plate) to the south enough to place the declination axis centered in the observatory. This will vary for everyone depending on your declination on the earth. I'm at 42.19.27 north... My offset is approx 6". So I will build my pier 6" to the south of center.

GEM Mounting - This is more complicated, but the idea is the same. You need to find the optical center of your mount when set up. Move the scope through all it's possible movements and visualize the "Center" that it rotates around. This point is what you want to be the Center of the dome.

Good Morning;
I slapped together a website last evening that has photos and sketches of the planned observatory. Comments are certainly appretiated.
www.adobecabin.com
The newsletter and photo sections have the bulk of the data. Feel free to comment on spelling - it was late :wink:

A 20" diameter pier!!! My 2 cents....I'd dig a 3 foot square hole, 3 feet deep, fill it with rebar and concrete, use the 20 inch tube and then neck it down to 12 inches about 2 feet below the top of the pier. IF you ever decide to mount a GEM, the 20 inch diameter pier will probably interfere with the scope.

As I said, just my 2 cents.

Haze: Why so low for the dome? I would think the lowest you'd want would be level with the peak of the barn. You're line showing the low viewing angle is actually wrong, since you're not taking the aperature into account.

Excellent point. The dome is kept low to minimize (as much as possible) the pier height. With that in mind, I have sacrificed the Northern sky to a certain extent based on a fellow astronomers comment that 'Nothing happens to the north you haven't had plenty of time to see". That comment plus the sky glow from Denver drove that decision.
As for the line origin...true as well. I drew that as an indicator of my clear line of sight. The actual telescope mount will have the z-axis about 12" higher than the line shows.
Does that make sense or am I missing your point?

Makes more sense. The way I see it, as long as you can see Polaris, you're good. Everything around there will eventually be higher than Polaris.

Well, I was told that my dome is in transit. Should be here by Friday...Hmmmm back to work

You might be one of the firts ones in the SW shippment route.....
Please keep us informedwhen the driver arrives :wink:

I couldnt live without all the galaxies in the north...I am more of a galaxy guy so the thought of losing some of the best in the nothern view would sadden me :roll: ...but then again...it is just me

The dome was delivered today. I was last on a list of 4 and the driver is on his way home. I am on my way to the hardware store for lumber.

:smt026 :smt026 :smt026 :smt041 :smt041 :smt041 :smt038 :smt038 :smt038

Now let's :smt079 and "gitter dun"...
Steve

Of course you know this means.....
PICTURES!

Rich

Seems Haze might be a bit "shy"??
Anyway, here is a link to his October/November progress.....

http://adobecabin.com/page5.html

Steve

Where will the ED go? Looks loke a roll off? Or is it a ED mounted on a Roll Off?-----> that would be sweet!!!