The home observatory

Although small telescopes can easily be stored indoors and carried out to the observing site, larger instruments need a permanent observatory. Refractors above 10 cm (4 in) and reflectors above 20 cm (8 in) are strictly nonportable unless dismantled, which is not recommended.

The first requirement for a home observatory is a suitable site. A roof top should be avoided, since this will subject the telescope to an unwelcome mixture of vibration and warm air currents from the building beneath. This reduces possible sites to the garden, where you should try to find an unobstructed horizon, taking into account trees, streetlights and so on. The form that the observatory should take can fall into one of three categories: the revolving dome, the run-off shed and the run-off roof. Although difficult to construct, the revolving dome offers maximum protection against stray light and the weather. For most reflectors, a run-off shed arrangement is suitable. It offers good protection against the weather when the telescope is not in use but is very exposed during observations.

A sliding-roof observatories (left) reasonably simple to make from a garden shed. It offers good protection for the telescope but not for the observer, who is totally exposed in winter. The roof should be opened toward the north to give a clear view of southern skies, and to the south for northern skies.


A domed-roof observatory allows a view of any part of the night sky. The walls of the structure can be made from treated wood and the dome, which must be light, reasonably strong and flexible, from sheets of aluminium.

Refractors and other tall telescopes are better housed in a run-off roof observatory. The high sides of such a building will not cause too much obstruction, since the height of the telescope will ensure that only a few degrees of sky will be lost from view.

Whatever type is chosen, the construction must be rigid. A good combination of materials is wood for the walls and clear, corrugated plastic for the roof. For long life and protection of your equipment, ensure that joints are waterproof.

Your observatory will require regular, routine maintenance. All moving parts must be kept lubricated and free from rust. Any exposed wooden surfaces should also be treated at least once a year with preservative or else be kept well painted.


All exterior wooden surfaces should be treated with preservative or kept well painted. A hinged roof shutter is the simplest method of creating an observing space for the telescope.
A wall flap swings down when the telescope is in use. The concrete base and rail are hidden by the structure.

An observatory such as this should not cause too many constructional problems for a handy person. An ideal size is about 2.5 m (8 ft) square. The base is made of concrete and the structure is built on a specially made iron rail mounted on wheels, which enables it to rotate.

Inside the observatory, keep clutter to a minimum. With some Newtonian reflectors, the eyepiece is on top of the tube, so you will need observing steps. If you have electric drive, a supply of electricity will be needed, but make sure that it is properly earthed. On a convenient inside wall, a mounted star chart will afford quick reference to many naked-eye stars.

http://library.thinkquest.org/21008/data/sky/home_observatory.html