[ecarfar]

Hi guys, I'm a newbie to this and would like to get an idea if my thought process is correct. I had been waiting for a while as the Skyshed POD was being developed. It looked like a good solution for my situation. I want to put an observatory on a portion of my existing deck that's about 16' x 16'. I was considering a Skyshed roll-off but the required rail extention would've made it too big. When the POD ordering went active earlier this week I hurriedly opened the order sheet and, to my horror, the total price of the XL-3 with shelves, delivered, was almost $2400!! Way much more than the original expected price. I found the Exploradome earlier this week and it seems to be the next best fit for me. I don't like the fact that it's so permanent, but I guess I could knock it down and preserve the old deck if I absolutely had to.

I'm going to be using a classic 10" LX200 with an 8" diameter, 36" high Astrosky pier (which will be about 32" off the floor) and, most likely, a Milburn wedge eventually.

OK, here's the plan. The base will be built according to the plans on the website: 10' x 10' with 4' high walls. I will be using the roof transition panels too. Now I plan on digging the pier hole in the exact center of the structure. I've seen pics of the LX200 on a Astrosky pier on a wedge and it looks to me like the centerline of the optical tube, when pointed at the zenith, it exactly in line with the pier. Will this provide a 360 degree view of the sky? Also, with the pier being 32" off the floor and with the wedge and mount, the scope height should be about 42" off the floor. Should I get a longer pier? 40"? Also, in your experiences with a building this size and in a similar situation, is there enough room in a corner to build a small warm room? Nothing big, just enough to sit down and close a door to warm up.

Anyway, thanks in advance for any help or guidance you can provide me. I do have some experience building things so gerneral contruction isn't too much of a concern.

Thanks,

Ed

[SteveDurham]

Ed...welome to our Forum, now yours also!!

First, Perhaps Neo could add his thoughts on pier placement with the LX200....He's done a real nice corner layout with his to determine wall height and offsets from center, if any. Neo???

Next, the deck....If you decide to build on it, you should definitly plan on separating the deck from the pier. If not, ANY movement on the deck will cause unwanted vibrations in the scope. If the deck is off the ground at all, I'd suggest a suitable size base, say 36" X 36" X 36", topped with some concrete filled chimney block at least 16" square up thru the deck. Then add the Astrosky pier to the top of the column.

Ideally, I feel the bottom of the shutter should be even with the bottom of the OTA when the OTA is horizontal. However, most of us cannot see thru the soup directly above the horizon anyway, so if the OTA has to "look -up" a little to see out the slot, nothing is lost.

I'm sure that others will chime in also...be patient.

Be sure to post images, so we know what you are describing. You could start with some of the deck....

Steve

[NeoDinian]

Ok, Ok...

What he's referring to with my corner setup is a test setup I did in my basement to determine offset, and height... Although I'm doing a roll-off, the idea would be the same...

I set up my scope in a "Mock-up" of my planned observatory and took many measurements.

 8x12_layout.jpg ( 17k ) Number of downloads: 2


Doing this, I determined that my OFFSET (Centerline of the scope on wedge compared to tripod center) is 6 inches. So when I build a pier, I will either offset the pier 6 inches to the south, or offset the top plate 6 inches with the pier centered.. One of the 2. This keeps the OTA centered.

For the height, you need to work everything backwards... Others here can give you the numbers needed. You need to know the height from the bottom of the lower shutter opening to the floor, as well as their wall height. With your tripod set up, you want to know what the height of the BOTTOM of the OTA is when set level in the forks... You want that number to be an inch or so higher than the slot opening height. This is your pier height. With those in mind, you have 2 options. Either adjust the height of the pier, or adjust the wall height to bring it to where you want... My thoughts on this, If the pier is too high, Raise the walls! (You don't want to go shorter). If the pier is too short, raise the pier and keep the walls to a minimum of the 4 feet.

You'll have PLENTY of room for a corner "Desk". Thats whats so nice about the 10x10 ED construction over the POD. You end up with valuable real-estate inside.

If you have any questions about what I'm trying to describe here, just ask.

[ecarfar]

Thanks for the welcome Steve. Yes, the pier will be attached to a cement filled sonotube, 12" (or bigger) in diameter as far as I can dig it down (6'?) and then, as it comes through the existing deck, the pier will not touch any part of it to eliminate deck vibration through the deck to the pier to the scope.

When I built the deck 15 years ago I put the joists 12" on center so I'm going to cut one out and box it and I will have a couple of feet around the joists to dig. The deck is maybe 18" off the ground. I would really like to do what you suggested regarding the 36" base, but it ain't gonna happen, it would require taking the deck apart and SWMBO has already relented this far I don't think she'll put up with that. The top of the concrete cylinder will be just below deck level just in case I want to restore the deck to it's old self in the future.

I understand it would be optimum to have the OTA just peek over the shutter, but, like you, my horizons are obscured and filthy so seeing within 20 degrees should be fine. I also didn't want to be too high and uncomfortable when viewing.

I will post some pics of the progresssion here and this weekend take some pics of the deck.

Ed

Ed...welome to our Forum, now yours also!!

First, Perhaps Neo could add his thoughts on pier placement with the LX200....He's done a real nice corner layout with his to determine wall height and offsets from center, if any. Neo???

Next, the deck....If you decide to build on it, you should definitly plan on separating the deck from the pier. If not, ANY movement on the deck will cause unwanted vibrations in the scope. If the deck is off the ground at all, I'd suggest a suitable size base, say 36" X 36" X 36", topped with some concrete filled chimney block at least 16" square up thru the deck. Then add the Astrosky pier to the top of the column.

Ideally, I feel the bottom of the shutter should be even with the bottom of the OTA when the OTA is horizontal. However, most of us cannot see thru the soup directly above the horizon anyway, so if the OTA has to "look -up" a little to see out the slot, nothing is lost.

I'm sure that others will chime in also...be patient.

Be sure to post images, so we know what you are describing. You could start with some of the deck....

Steve

[ecarfar]

Thanks Neo, I was doing last night what you did. I have my LX200 on the tripod and was measuring for everything. The only problem I have is that I don't have the Milburn wedge yet so I don't know how much height that will add overall. I've attached a pic of the Astrosky pier and an LX200 on a wedge and it looks as though the OTA isn't offset at all. Am I correct?

I understand your point about not wanting the scope too high, but I guess it's better finding it too high than too low. I may have to wait for the pier to arrive and ask Milburn for wedge specs so I can determinie the wall height. I should probably just order a 40" pier and work the walls around that.

Ed

Ok, Ok...

What he's referring to with my corner setup is a test setup I did in my basement to determine offset, and height... Although I'm doing a roll-off, the idea would be the same...

I set up my scope in a "Mock-up" of my planned observatory and took many measurements.

 8x12_layout.jpg ( 17k ) Number of downloads: 2


Doing this, I determined that my OFFSET (Centerline of the scope on wedge compared to tripod center) is 6 inches. So when I build a pier, I will either offset the pier 6 inches to the south, or offset the top plate 6 inches with the pier centered.. One of the 2. This keeps the OTA centered.

For the height, you need to work everything backwards... Others here can give you the numbers needed. You need to know the height from the bottom of the lower shutter opening to the floor, as well as their wall height. With your tripod set up, you want to know what the height of the BOTTOM of the OTA is when set level in the forks... You want that number to be an inch or so higher than the slot opening height. This is your pier height. With those in mind, you have 2 options. Either adjust the height of the pier, or adjust the wall height to bring it to where you want... My thoughts on this, If the pier is too high, Raise the walls! (You don't want to go shorter). If the pier is too short, raise the pier and keep the walls to a minimum of the 4 feet.

You'll have PLENTY of room for a corner "Desk". Thats whats so nice about the 10x10 ED construction over the POD. You end up with valuable real-estate inside.

If you have any questions about what I'm trying to describe here, just ask.

Attached File(s)

 LX200GPS_Astrosky_Piersm.jpg ( 24.56k ) Number of downloads: 0

 

[NeoDinian]

You are correct about that pier... The top of the pier itself is offset to compensate for the OTA offset. IF there is any difference (due to your declination, or the wedge difference), it would only be an inch or so...

Yeah, it would be best to wait till you have everything. This way you can get all the correct numbers and not have any problems later.

[ecarfar]

Yeah, it'll probably be better to wait. The wedge is the only variable I really can't predict. I'm going to bug them for some measurements!

Thanks again,

Ed

You are correct about that pier... The top of the pier itself is offset to compensate for the OTA offset. IF there is any difference (due to your declination, or the wedge difference), it would only be an inch or so...

Yeah, it would be best to wait till you have everything. This way you can get all the correct numbers and not have any problems later.

[ksmith033]

Congrats on your decision to put up an ED, and welcome to the group. I too have an LX200, but mine is mounted on a Meade wedge. My offset is about 9.5 inches, so I off set my pier 9.5" to the south. But, as you and Neo agreed on, that pier looks like it has the offset built into it. That's good in case you ever decide to "upgrade" to a GEM in the future. I would have to drill into my concrete footing and glue bolts in for a new pier location, but I don't see that in my budget anytime soon. Best of luck, and (like Steve said) post lots of pics!

[NeoDinian]

Yeah, you have a 14" scope and at a different latitude than me... A 10" LX200 at 42 degrees north works out to about 6 inches..

[Pete Peterson]

Neo's experimental layout in his basement was well thought out. There are many variables in laying out an observatory, including your latitude, the specifics of your wedge, the size of your scope, the range of eyepiece heights through which you can view comfortably, and the minimum viewing angle desired.

The best ways to work out pier position and wall height is by putting the scope on the tripod mounted wedge and then experimenting and measuring. The height of the bottom of the shutter opening is a good distance above the dome skirt, and that must be factored in also.

If you are thinking "octagonal shape" to conserve deck space, consider a semi octagonal with 2 chamfered corners and two full corners. For an example see Wishing Star Observatory in the ED construction section of this website, or go to my own construction blog at www.peterson-web.com/wish

Best of luck. The ED is the way to go.

[ecarfar]

Hi Pete, yes I did see the pics of your Ob a few days ago, very nice. Mine will be similar to yours, near the house like yours and covered in matching vinyl siding. I am going with a full square design though. My deck is large enough to fit it.

Neo's experimental layout in his basement was well thought out. There are many variables in laying out an observatory, including your latitude, the specifics of your wedge, the size of your scope, the range of eyepiece heights through which you can view comfortably, and the minimum viewing angle desired.

The best ways to work out pier position and wall height is by putting the scope on the tripod mounted wedge and then experimenting and measuring. The height of the bottom of the shutter opening is a good distance above the dome skirt, and that must be factored in also.

If you are thinking "octagonal shape" to conserve deck space, consider a semi octagonal with 2 chamfered corners and two full corners. For an example see Wishing Star Observatory in the ED construction section of this website, or go to my own construction blog at www.peterson-web.com/wish

Best of luck. The ED is the way to go.