Observers need to be prepared to face nighttime observing conditions, even if those conditions are merely those of the friendly backyard. This preparation mostly consists of staying warm and keeping insects at bay. A CAT user who is freezing cold or being bitten by skeeters will forget plans for an all-night Messier marathon in a hurry and soon be back inside watching TV.
Even in the summer, keeping warm is a necessity. It's sometimes difficult to believe a person could get uncomfortably cold on an August night in the deep South. But no matter where the observing site is located, cold is always a factor. Observing means being out under the open sky and standing nearly stock-still for hours on end. Always dress more warmly than seems necessary. When observing from home it's possible to run inside occasionally and warm-up, but that gets old in a hurry. Not only does carefully planned observing come to a screeching halt just when the sky's getting good, dark adaptation is wrecked.
How do astronomers stay warm? Climate will dictate exactly how to dress, but always dress in layers. Layers of clothing rather than one heavy coat or sweater help the body retain heat. Much of the body's heat loss is through the feet, so take special
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DOI: 10.1007/978-0-387-09772-5_8, © Springer Science + Business Media, LLC 2009
care to insulate them. On a mild evening, that may be as simple as putting on a pair of wool socks to help isolate the feet from the cold, cold ground. On bitter nights, boots designed for harsh conditions may be required. Even more heat is lost is from the head, so keep it protected with a hat—a fuzzy cap or a "watch cap" is better than a baseball cap, but anything helps.
Keep the body's insides warm on bitter nights, too. On cold evenings a thermos of hot liquid will be most welcome in the wee hours. According to the experts, the best beverages are caffeine-free, like hot cider. For some people, caffeine can adversely affect the body's ability to retain heat. Don't drink alcoholic beverages. They dilate blood vessels in the skin, causing the body to lose heat more quickly than normal— even though you think you feel warmer for a little while after a shot of whiskey. Alcohol also seems to have a bad effect on dark adaptation. Save the Rebel Yell Bourbon for after the observing run.
Bugs? Depending on the climate, mosquitoes can be a serious problem. In subtropical or tropical areas they can easily halt an observing run. There's no shortage of advice from astronomy club buddies on how to keep the skeeters at bay, and store shelves are crowded with preparations guaranteed to keep the little suckers from biting. There are no magical remedies; only one thing makes a difference: DEET. "DEET" is the abbreviation for a chemical called "n-diethyl-m-toluamide," and a repellent that doesn't contain it will not work. Be careful with DEET-based repellants, though; they act as solvents and can ruin plastic, paint, and maybe even optical coatings. When it's time to spray on the stuff, move downwind of the scope. Also, wipe repellent off fingers before touching the telescope or eyepieces. (In most cases, it's not necessary to bathe in repellent; a light spraying will do.).
Preparing the CAT If you've read through the earlier chapters, you already know the basics: allow the scope to acclimatize to outdoor temperatures, set up in an area protected from ambient light, and be prepared to deal with dew. One last thing: make sure everything that will be needed during the evening's observing is close at hand. Eyepieces, charts, and other items should be positioned on a table so you don't have to get up from the observing chair to get at them. If accessories are not easily available, they won't get used, and the considerable sums spent during accessory buying madness will have been wasted.
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