There are probably three main types of observatory structure in common use by amateur astronomers. All have their plusses and minuses - in the end it comes down to personal preferences (and depth of pockets).
These three types are the dome, the shed (with roll-off roof), and the run-off shelter. At the end of this article I will do a bit of a comparison between these, and note a couple of other alternatives.
My current observaotry is a dome (a 10 foot diameter SkyDome) which was erected in 2015. I purchased it second hand from a local astronomy buddy. There was some effort involved in breaking it down in his garden, transporting here, and re-erecting. Luckily it all fitted in one of the big Transits.
The installation is a little unconventional. I was not sure where to put a pier, and I quite liked the idea that the scope could be taken out and set up elsewhere if needed. So I took a page out of John Fletcher's metaphorical book, and laid out three deep concrete pads with a small paving slab on top of each. These are the bases for the tripod. Then I laid paving slabs around the peripehery of the dome (these had less heavy foundations). The dome base is bolted down onto these to assure it won't blow away. Getting the slabs properly level is importatnt to make sure the dome will run nicely. I then made a floor by laying 2x4 joists across the width of the observatory, and covered these with flooring T&G chipboard. Cutouts were made to expose the pads for the tripod.
Originally the telescope in the observatory was a Meade LX200 ‘classic’, but in 2019 the RA drive failed, and so I have replace this with a second-hand Lormandy G11 mount and a second hand Celestron C11 XLT. The LX200 OTA has been de-forked and should come in handy as a ‘portable’.
Before I had an observatory, I used to set up my equipment every night in the back garden, or head out to a dark observing site. With a small dobsonian type telescope this is not too much of a chore, but setting up and aligning an equatorially mounted scope can take a while and can be off-putting after a long day at work.
When moving to our current location, a place without much light pollution and a space in the garden for an observatory were high on my shopping list.
My first observatory was a fairly traditional run-off roof affair. I built this from scratch with a central pier made from concrete blocks, topped with a paving slab to hold my 20 inch Dark Star dobsonian telescope. It might sound strange having a big dob in an observatory, but it was 1) heavy - so you did not really want to have to lug it out everytime you wanted to observe, and 2) being a truss-tube dob, there was always some element of re-collimation needed every time it was set up. So having it permanently set up meant it would get used a lot more. The roof rolled off on scooter wheels, running on L channel. The roof was bitumen corrugated sheets from Wickes, which pretty much self supported themselves.
Thoughts on types of observatory
Here are some pluses and minuses - from my point of view anyway
|Dome||It's a dome||Restricted view of the night sky|
|Good protection from wind||Need to move dome to follow objects|
|Quick to get going and close up||Maybe not a DIY job|
|Efficient use of space in the garden|
|Usually fibreglass, so lasts well|
|Roll of roof shed||Full view of the night sky||Limited protection from the elements|
|Can be quick to open up||Roof can be heavy to move|
|Easy DIY job||Not many commercial offerings|
|Good for remote controlled imaging||Usually made of wood, so needs regular maintenance and maybe limited lifespan|
|Roof needs to cover someplace when open, which may be dead space|
|It's not a dome|
|Roll off shelter||Can be small and compact||No protection to observer or equipment when open|
|Easy DIY job||Ground level runners can stick|
|Can be cheap||Not a dome|
|Good for remote controlled imaging|
Some other peoples observatories
- Richard Miles has an intersting ‘clam-shell’ design that just houses his telescope. https://britastro.org/user/479
- Doghouse roll-off roof mini-observatory as seen in Sky & Telescope magazine. https://skyandtelescope.org/astronomy-resources/a-simple-backyard-observatory/