Don became interested in astronomy at age 8. He received his 1st telescope in 1965, a 2-inch (5cm) refractor. Later he received a 6-inch (15 cm) Criterion Dynascope and found all the Messier Objects in one year (1969-70). He began his 1st comet hunting program in 1975 and found his 1st comet in 1978, after 1700 hours of searching. His 2nd comet took an additional 1742 hours. He ultimately discovered a total of 12 comets, which bear his name.
In 1978, Don was one of the independent inventors of the Messier Marathon, an attempt to find and view all 110 galaxies, clusters, and nebulae in one night. In the last 40 years of his life, he completed over 50 Messier Marathons and wrote 2 books on the subject.
Until the end of his life, in 2022, Don continued his visual comet hunting and Messier Marathons from Arizona, where he lived with his wife Michele.