Instruments

Comet hunters generally agree that the instrument is not nearly important as the person behind it. I have found that eyes, skies and instrument determine what you see, and the comet hunter should try to improve all three of these areas. I started with an 11 cm, f/5 reflector at 20x.

The Machholz ObservatoryThinking that a larger instrument would help me see fainter objects, I purchased a 25 cm f/3.8 mirror and built a reflector telescope around it. When I started using it in October 1975, it was one of the largest instruments used for comet hunting. This has changed as others are now using larger scopes. Finally, in May 2006, I found an ad in a newspaper for an 18-inch (47cm) reflector, f/4.8 for sale. I purchased it and for the first time in 31 years I had upgraded my aperture. I now use this instrument for most of my comet hunting.

In April 1983 I purchased two aerial photography lenses, rated at 36" (914 cm) fl, f/8. Each consists of five elements, the front being a lens of 6.2 inches (157 mm). From these I designed and built a pair of binoculars. Based in a plywood box, each light path consists of one aerial photography lens, one 2.60" diagonal mirror, one 1.83" diagonal mirror and a surplus eyepiece slipped into PVC pipe. The instrument cost under $400 to build, and I've used it for more than half of my comet hunting since then. The contrast is good, and under moderate light pollution conditions it sees as well as the 25 cm reflector (under darker skies the 25 cm performs better), and I can sweep faster with two eyes than with one. It is mounted on a large altazimuth pipe mount. The 47 cm reflector sees about two magnitudes fainter than does the binoculars.

Don's 18-inch Dob The 25 cm reflector had gone through some changes too. In 1981 I redesigned the tube, removing the focuser and using a pipe flange "sunk" into the side of the tube. This brought the eyepiece closer to the diagonal, so I reduced the size of it from 3.14" to 2.14". I've used a few homemade eyepieces on this instrument, one of them gave me about 36x and a 100 degree apparent field of view, an actual field of view of 2.8 degrees.

In 1988 I built a 12 cm refractor out of an additional aerial photography lens. Well-baffled and in a plywood box, a rotating turret allows me a choice of eyepieces. I most often use it at 20x, but seldom see much fainter than the Messier Objects. It was used, however, for the discovery of Comet Tanaka-Machholz (1992d).

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