Last week, I started a series of blogs devoted to helping you construct a home observatory. One of the most important considerations involves choosing a site. Of course, you want the best overall location for your observatory, but is that 50 feet out the back door or 50 miles away at a dark site? The location must work for you. It must allow you the freedom to observe whenever it's clear. Because of that, generally, a closer location works best.
Now, setting up an observatory in your yard — unless you're one of the fortunate few who live 2 hours east of Tucson — will involve some considerations: limiting visual magnitude; buildings and trees blocking some sections of sky; even direct light from other homes, security lights, or streetlights.
Regarding visual magnitude, in my blog post for April 16, 2007, I talked about the multitude of targets available from city skies. I can't tell you how many wonderful nights (and days, observing the Sun) I spent under El Paso's relatively bright magnitude 4.5 sky.
Before you start construction, take a survey of your yard and surroundings. You probably have no say over where existing buildings sit, but moving your observatory just a few feet one way or another can improve your sight line dramatically. As for trees, I'm not an advocate for slash-and-burn clearing, but I would sacrifice one for my observatory's benefit.
A few direct lights will pose the least of your problems. Such lights fall under the category "light trespass," rather than light pollution. You can eliminate problems from most individual lights by carefully calculating your observatory's wall height.
Next, you have to decide whether to build an observatory that simply houses a telescope or make it larger and able to accommodate people. If you plan to conduct only astrometry or photometry of asteroids, and you know a CCD camera will stay connected to the telescope all the time, you won't need a larger structure. If, however, you're like me — more of a social observer who likes to have friends over — take that into account in the design process.
Next week, I'll give you some tips on how to plan your observatory's size.