Shield Your Site

The same principle works on large scales. Early on a clear morning, have you noticed grass in the middle of a field white with frost or dew while grass near a tree has none? The tree is a giant dewcap, and it can work for you too. If you'll be looking at just one part of the sky, try to have trees around and behind you. Not only will your telescope stay dry longer; so will your charts and accessories.

Trees also reduce wind problems, but a slight breeze is a good thing: it will keep your telescope nearly up to the ambient air temperature, since radiational cooling is slow and inefficient compared to heat transfer with moving air.

Then there's the observing umbrella, not a widely known accessory but one that works. A beach umbrella blocks the chill of outer space the same way it blocks the heat of the Sun. It can help shield all your gear and you too from the cosmic deep freeze. On a still night a thermometer under an umbrella can read more than 10° Fahrenheit (6° Celcius) higher than when it is exposed to the open sky.