Observatory is it worthwhile for me?

[starpusher]

I live where the sky is not great i.e. near a city and light polluted. On a “good, clear” night, I don’t think I can really see the Milky Way from my back garden but I would really like to have an observatory. I am trying but I am not there yet with the astrophotography and imaging is what I want to do, particularly deep sky. If I do the observatory project it will be quite a few months on, demolishing an old garage, sorting other things, etc., so I am in no rush. What I can’t decide on is if it is worth it for me because of the light pollution. If any one can advise then that would help me decide.

Thanks,

Richard

[brianb]

If you're really keen on imaging, I think you need an "observatory" of some sort - it takes ages to align an equatorial mount accurately enough for long exposure imaging, you don't want to waste that time every session, so you at least want the mount set up permanently, even if you take the tube off the mount for storage. An observatory will also keep the wind off the scope, this will allow you to image on some nights when the wind vibration would be impossible otherwise.

As for light pollution, imaging using narrow band filters is one way of working around that problem, though that means longer exposures still, making the observatory even more valuable.

If you can find a spot with good views, have the expertise to knock something together and can obtain any necessary planning permission, go for it.

[barkis]

Hi. Richard,

how long have you been into astronomy?

If it's years, then you are not just in a phase, but very into it, and if so, then If I were you, I would consider it a worthwhile project.

If you do go ahead with the build, then make it not only to house the Instument you own now, but for the size you might own in the future. And don't forget the mount. Also, icorporate a warm room, where you can be comfortable, and control the Imaging from there.

Plan for the future, not today, and as far as light pollution is concerned, it can be beaten to some extent, and If you look around the Astro world on the net, you will find great images that have been taken in light polluted skies. Start planning your Obsy, there is no rush, and you will enjoy doing it. It really will add a whole new dimension to your astronomy.

Ron.

[LaVey]

hi richard... I would say go for it.. I am in the same kinda boat as you, I live in a very light polluted city next to an airport! My imaging is coming along slowly.. but I think the building of an obs will really make a difference to how much time I can put in because of the set up times everytime.

[Dave]

Go For it! You definitely wont regret it.

I live in light polluted skies, but my observatory makes getting out there much easier, not having to set it all up every time, so I can be out and looking within a few minutes if necessary and make the most of even a small gap in the many clouds. And once you get into imaging, it can be frustrating with all those lights, but with perseverance you can produce some great images.

[Psychobilly]

Definetly it gives you something else to look at in the rain....

LP can be successfully tackled by a variety of means... I have a 30s sky without filters and a reasonable 300s one with...

The obs just makes setup and close down (when it clouds over or starts to rain) a lot quicker...

Peter...

[tinvek]

you've got to go for it if your serious, especially if you have limited opportunities just because of the saving in setup time.

plus it's a type of shed and everyone should have one proper shed in their life

[starpusher]

Great.

I rang the chap at Pulsar today to ask about a suitable base for the observatory (dome type with a fixed pier). He thought that if I were to install the pier and dome on my old garage concrete base then that should be fine provided that I was not planning to do what I think he said was very fine resolution imaging . I know the concrete base is sound and rigid, 4-6 inches thick in the middle and probably 10-12 inches thick at the edges because I laid it myself about 20 years ago. But I know some people build observatories with the central pier base mechanically isolated from the main observatory base. I think this is to stop possible vibrations induced in the main base travelling up the pier and into the scope and reducing image quality. Does anyone have any thoughts on this? Thank you all for your comments so far.... I am very encouraged.

Regards,

Richard

[barkis]

Some have buried their scope pier into 3 foot cube of concrete Richard, and the mount should preferably, be isolated from the surrounding floor. However, once your pier is bolted securely to a four inch pad of concrete, I don't think it will tremble unless severely shocked.

When you are imaging, and taking your subs, you will be sitting quietly at your lappy, and not galloping across the dome floor. I presume your dome will be fixed to the same cocrete slab as your pier, so any high winds buffeting the dome may transmit some movement to the floor, but you would not be imaging in those conditions anyway. I think I would risk it, but more input will follow no doubt.

Ron.

[Dave]

Your base should be fine as long as you don't dance around inside your observatory while imaging like I do...

[Psychobilly]

mines got a silly amount of concrete (well over 600kg) under it and 5 foot long steel piles cast into that and the surround is isolated with a 2" gap but when trying to image at 60fps at f30 the other day i did notice some trembling when i jumped up and down on the obs floor... possibly because the obs is sitting on built up ground about 10 feet above the "grade"... more probably because i'm a Fat ***

Peter...

[Merlin66]

Definately worth it!

It allows all the gear to be safely stored and ready for use when the weather clears...

I compromised and used a 8'x6' Argos Tin Shed as a base for a run off roof observatory. Works extremely well and very cost effective!!

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[starpusher]

Have done a couple of drawings... what do you think?

Regards,

Richard

observe.pdf

[barkis]

Great plan Richard, and it looks very similar to what I did myself many years ago. My garage still exists, but the Observatory I built on to the end, has now been turned into a workshop.

The main difficult I had with the dome was, the base ring for the bearings, was supported on each of the four walls, and the surrounding flat roof was difficult to seal around the ring. The dome skins were galvanized sheet metal, and quite heavy, so moving the dome around, tended to break the water tight seal, therefore I was forever battling water ingress. Sealing it was just impossible, so I suspended a ducting inside the dome underneath the bearing ring, so any rain water getting through, was captured bu the duct, and removed to the outside through a pipe into the garden. It worked well. That large concrete plinth for the scope mount, will be very heavy, and you will need to ensure that the existing floor will carry the weight, and not crack eventually. Another thing I would suggest, is to put a suspended wooden floor all over the dome area, and fitted around the mount.

Rather than make the mount base a solid lump of concrete, why not build a double brick wall up to the height you need, pack two thirds with rubble and ballast, cap the top with 6 inches of concrete, then place a steel plate across the top, which would rest on the bricks and not the concrete cap. Any bolts for fixing, could be set into the cap before it sets. Corresponding holes drilled into the metal to fix the scope mounting. Most of this base for the mount, can be hidden underneath the wooden floor, but the floor is best kept separate from the base.

Feel free to reject everything I've said here mate.

Ron.

[michaelmorris]

Richard

Both plans look great. I guess the choice on which to go for will depend on your budget, how long you think you'll stay in the house and whether you can sort out a workable method of sealing the doom/pitched roof interface on the garage conversion.

I agree with Ron about the suspended wooden floor around the base of the pier. This should be relatively easy (but time consuming) to construct. On the garage option why don't you just use a large diameter steel tube as a pier. This could be bolted to directly on to the concrete floor. You could fill it with sand to reduce resonance vibrations. For a metal pier should ideally look to have a pier diameter at least as wide as the diameter of the largest scope you think you might ever want to mount on it.

I agree that it would be best ot try to isolate the pier from any floor slab. If you can't, thick carpet with foam underlay and/or rubber matting should help reduce vibrations caused by walking around whilst imaging.

Building an observatory has changed my hobby beyond recognition. I spend much more time observing and imaging and setting up/putting stuff away takes just a few minutes.

I would spend a lot of time planning your observatory before committing to anything. Think about electrics (think about how many sockets you'll need then treble it!), internet/remote access (wireless access will often not work away from the house) layout, heat management (inc. insulation and ventilation), water management (keeping it out!), security, easy of maintanence and try to make it as future proof as possible.

Enjoy.

[starpusher]

Ron,

I like the idea of the double brick wall, rubble plinth / pier. It would be easier to demolish and remove at a later date, if necessary, than a solid concrete lump. So for option 1 this plinth will probably have to be fairly high from ground level to my heq5 mount. This plinth may have to be 5 feet high? But at that height it probably should be fairly wide for stability (3 feet)? If this were solid concrete it would weigh 2 ½ tons. I suppose a brick rubble construction then it would be less, say 2 tons and that is about ½ ton heavier than my car. If that weight were on the existing base, concentrated on a 3 foot diameter circle then it may cause cracking. Maybe I could build it up on lintels / beams spreading across the garage floor to distribute the load. How thick would you expect the steel plate to be?

Michael,

I also like the steel tube again 5 feet long (?) but I have the feeling the diameter should be fairly large and I would not know where to get such a beast. We expect to stay in the house for at least another 10 years.

My initial thought was to demolish my old concrete garage and start from scratch. I have the dilemma of deciding whether to keep the old garage, replace the roof and make option 1 work or go for option 2. The old garage walls may last for another 10 years but by that time if we do sell the house the buyer will probably want to knock it down the old garage and rebuild anyway so accounting for that it makes option 2 more attractive. I think if I go for a new garage and option 1, then that will be pricey so that brings me bake to my initial thought …..Demolish the old garage go for option 1 i.e. no big plinth, platform and lintels. I could even have option 1 as a fabricated timber construction bolted together so the whole lot could be moved with us if we moved house in 10 years or so.

Regards,

Richard

[barkis]

Richard,

As an alternative to a steel tube, you may wish to consider High pressure water pipe. I have my Meade LX90 12" and Superwedge monted on a pier made with this stuff. It's walls are 26mm thick, and it drills and taps easy, if there is a need to do so. I have in the ground in a concrete base 18" deep. But, I have also a surround of bricks to a height of 14" and that too is filled with concrete. You can't make it shudder with a sledgehammer.

The pipe colour code is Blue.

Ron.

[George]

... more probably because i'm a Fat ***

Peter...

I didn't want to point that out

[Psychobilly]

[RobH]

As others have said, an observatory is a great asset.

I would personally isolate your pier from the rest of the structure, you may regret it at a later stage if you don't.

My pier, in theory, is connected to the rest of the structure as the observatory is built on top of a concrete base that also has a 1 metre cubed lump of concrete sitting on it that the peir is bolted to.

The observatory itself is bolted to the concrete base, but nowhere does the observatory floor contact the pier or concrete block.

The pier itself is an 11 inch diameter steel tube with a 1 inch thick steel base and is filled with a sludge of sand and engine oil.

It's isolated enough that I can dance the hornpipe in there (if I want )

It doesn't move at all!

I too looked at going down the dome route but decided against it in the end for several reasons.

1. Security. The best security is if no-one knows you have an observatory. A dome gives the game away immediately, but a roll off roof shed just looks like a shed, and doesn't attract any attention.

2. I like to see the whole sky, especially on mild summer nights. I often sit back while the scope is imaging and just scan the sky with binos.

3. A dome needs to be motorised, or you need to be going out at regular intervals through the night to move it.

4. Cost. A ROR is cheap!

Domes do have 1 big advantage though...protection from wind. With my ROR observatory, although there's some wind protection, it's nothing like as good as a dome in that respect.

Cheers

Rob

[starpusher]

Ron,

What is the pipe made from and the diameter? Is yours a high pier?

Regards,

Richard

[starpusher]

Rob,

It sounds as if your scope is high from ground level,if the pier is mounted on a 1 metre cube. I also have the same reservations about the dome but I do like the shelter principle. We do have 4 dogs (Heelers) and if anyone comes down the drive then the dogs let all hell loose with the barking.

Regards,

Richard