Named for John E. Bortle, an American astronomer specializing in comets and variable stars. One of the great visual observers, he has made more than 2,000 observations of approximately 150 cometary apparitions over the course of three decades. He has often been first to report unusual cometary activity and is well-known for his analyses of visual magnitude estimates of comets. He has also reported tens of thousands of variable star observations. Bortle has written the Comet Digest column in Sky and Telescope for more than a decade and has edited the American Association of Variable Star Observers Circular since its founding in 1970. (M 17659) _ _.