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Don Machholtz: A Visual Comet Hunting Program

Donald Edward Machholz is the most successful living visual comet hunter in the United States, being credited with the discovery of 11 comets, including the periodic comets 96P/Machholz, 141P/Machholz, the non-periodic C/2004 Q2 (Machholz) that was easily visible in binoculars in the northern sky in 2004 and 2005, and most recently, C/2010 F4 (Machholz). Machholz is also considered to be one of the inventors of the Messier marathon, which is a race to observe all the Messier objects in a single night.

It was 33 years ago that he decided to pursue a systematic search for comets. This decision came at a pivotal time in his life. He had just finished serving three years in the military, had moved back home, and he wanted a project that would encourage him to spend more time viewing the heavens. Over the previous decade he spent considerable time viewing all the planets and a half-dozen comets, found every Messier Object in one year (1969-70), and photographed the skies. He has always enjoyed the view of the night sky through the telescope.

The projects that he considered were: variable stars, asteroid studies, and comet hunting. Comet hunting seemed most appealing to him. He also knew that very few Americans were searching for comets, because most visual discoveries were being made from foreign lands.

According to James Muirden ("The Amateur Astronomer's Handbook"), the average comet hunter took 300 hours to find a new comet. This was confirmed to him when he read an interview with William Bradfield appearing in the magazine Eclipse. There he said his first discovery took 260 hours and his second took an additional 306 hours. Don's early philosophy developed: he would attempt systematic comet hunting for as long as he found it enjoyable. If he did not find it enjoyable, he could quit my comet hunting program and move on to something else, his only "loss" being the time spent looking through the telescope. And if he enjoyed it, he'd continue his comet hunting program. Finally, he wanted his comet hunting program, as extensive as it might become, to be only a part of his life, not to consume it. He did not want to exclude other activities or people from his life just because he wanted to hunt comets.

Don's website:

Don recounts his legendary comet hunt as well providing tips and charts for other aspiring star gazers in his four books.

Books by Don Machholz are:

  • The Observing Guide to the Messier Marathon: A Handbook and Atlas

  • Messier marathon observer's guide: Handbook and atlas : a complete guide to running your own Messier marathon

  • Decade of Comets: A Study of the 33 Comets Discovered by Amateur Astronomers Between 1975 and 1984

  • An observer's guide to comet Hale-Bopp: Making the most of Comet Hale-Bopp : when and where to observe Comet Hale-Bopp and what to look for