Building Your Own Observatory

Given the climate and weather in my part of the world (Ireland), the above scenario is all too common. And, if it happens too many times, you might be tempted not to use the scope at all because you're likely as not to have to lug it back into the house just after you've gone to the trouble of setting it up. I sometimes wonder how many telescopes languish in bedrooms, kitchens or garden sheds for this very reason.

And if you think that the time spent setting up a basic telescope is too long, imagine what it takes to configure a telescope with a GOTO system, especially one that's properly polar aligned. And then add to that the time involved in getting the system ready for some CCD imaging. With my weather, that's just asking for trouble!

Being interested in film and CCD astrophotography, this was the situation which I faced back in 1999. Learning the ropes in CCD imaging meant the CCD setup alone could take anywhere from 30-60 minutes! (Experience has since refined that time down to 10-15 minutes). A number of factors soon convinced me that what I really needed was a permanent observatory. Some of these factors included: an ability to quickly cover all exposed equipment in the event of rain; protection from the wind; somewhere to leave the telescope permanently set up in readiness for the next observing session and an external mains outlet to power items such as the CCD camera and laptop. The telescope GOTO system is powered by a car battery - a heavy enough item which I didn't want to lug from the house to the bottom of the garden and back again at the end of an observing session.

My telescope came with a field tripod - a reasonably sturdy aluminium affair that is fine for field work; i.e. bringing to a dark site and performing simple visual observations. However, it's not really suitable for a permanent setup. Kicking one of the legs in the dark would be enough to put it out of alignment, especially where the fine tolerances of CCD imaging are concerned.

Realisation

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It soon became apparent following numerous setups and breakdowns of the equipment in the back garden that a lot of observing/photographic time was being lost in these exercises let alone the chore it can become in packing everything away when you're exhausted and the only thing you want to do is go straight to bed.

So I began contemplating the idea of building my own observatory. Now my DIY abilities have been confined to a number of unfinished projects (like building a coffee table or a TV/video unit) and a couple of projects that did see fruition - a small bookcase and a Pergola out in the back garden. The fact that the pergola was still standing two years after I built it, despite howling gales and such suggested that my meagre skills might just extend to building an observatory after all.

The DIY Approach

A couple of years earlier, I attended a basic woodworking course in the hopes of picking up some simple skills. The fact that the lecturer's first words were: "Welcome to the woodwork course. The first thing I want you to know is that I'm not going to teach you about making joints. Just tell me what you want to build and Ill help you as best I can." didn't fill me with confidence. Maybe I'm naive, but I figured woodwork is all about joints because that's what holds everything together. Needless to say I didn't stay too long on that course. That and the lecturer's obviously increasing ineptitude sealed its fate.

What little woodwork skills I do have I've picked up from reading a number of books on the subject. That and having the right tools (not trying to hammer in nails with the blunt end of a screwdriver, for instance), were the key to this project.

I hunted around the Internet and in old astronomy magazines for articles written by anyone who'd attempted something similar. It came down to two basic designs - either the observatory would have a dome or a roll-off roof. I didn't fancy the logistics involved in designing my own dome and commercial units were just too expensive. Besides, whatever dome I would have ended up with would require some mechanism to rotate it synchronously with the telescope. That was way beyond my capabilities.

The roll-off roof design comes in various guises. It has the advantage of being relatively easy to build and, once the roof is rolled off, there are no worries about the opening having to track with the telescope. So that was the design I decided to go with.

Finding the Best Location

The re-excavated pier hole which was widened to 1 metre (3 feet) from 60cm (2 feet) on my second attempt at building a pier base. The remainder of the original DIY metal tube still protrudes from what's left of the concrete.

Before doing anything, though, I had to choose a site in the garden that was reasonably protected from street lights and neighbour's security lamps. Fortunately, the garden is sunken - not by design but by subsidence - which affords protection from security lamps. Street lights are a different matter. Four such lamps shine into the garden. At three positions in the garden, trees and bushes provided some shade from the lights, but at each position, one street light (a different one at each position!) was still intrusive.

One position provided a view primarily of the northern sky. Bushes blocked out the southern sky and the house blocked the western sky. Since Dublin city washes out the northern sky with light pollution and there was no view of the southern sky, this site was rejected. The second position afforded a good view of the eastern and northern sky but not to the south or west. This site was rejected as well. The third position provided good views of the southern sky, very little of the northern and some of the eastern and western sky. This was the site I chose to use for the observatory.

Before I could build the observatory, I would have to find a suitable permanent mount for the telescope. I decided to build a mount myself (in true DIY fashion). All the articles I'd read on this subject suggested sinking a metal tube into 60cm-100cm (2-3.5 feet) deep concrete. To cut down on vibration, the tube should also be filled with concrete.