Another mandatory item for the CAT user is an astronomer's flashlight. Just any flashlight will not do for reading charts, operating the telescope, assembling/disassembling the CAT before and after the "run," and performing the other tasks that must be done on dark fields. The perfect astrotorch puts out a pure red beam that is dim enough not to harm dark adaptation. A too-bright red light can be nearly as harmful to night vision as a white light.
What to do? Some novices try covering the lens of a standard flashlight with layers of red cellophane or transparency film. That works but is not an optimum solution. Usually, the light is either too bright or too dim, and it is rarely very red. The best choice is a red light-emitting diode (LED) light sold specifically for use in astronomy (Plate 40). These flashlights give off a very pure light, are usually equipped with a dimmer control that will allow them to be adjusted for optimum illumination level and include features of vital interest to observers—such as neck straps—that are not common in "normal" flashlights.
Any astronomy seller will have scads of red lights for sale. Anacortes Telescope and Wild Bird, for example, lists 15 different astronomy lights on their Web sites. Which one is best? A good flashlight has both red and blue (or white) LEDs. With a flip of a switch, these can be changed from red to blue/white, helping you walk back to a cabin, tent, or car safely when you are done on the observing field. A current favorite is the Rigel Systems Skylite ($31). It has all the features you would want, four LEDs (two red, two blue-white), a strap, a dimmer control, and a sturdy housing.
It gives off a great deal of light when it is needed, but since it uses LEDs, it is very miserly in its consumption of batteries. There are plenty of cheap imported clones of the Skylight, but the genuine Rigel is by far the best.
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