Andrew Cooper
Apr 16, 1999    Organ Pipe Cactus National Monument, AZ (map)
20cm f/10 SCT

Large and round with a sharp, brighter nucleus, otherwise fairly dim

Charles Messier
Apr 13, 1781    

Nebula without star, of the same light as the preceding [M99], situated in the ear of Virgo. Seen by M. Méchain on March 15, 1781. These three nebulæ, nos. 98, 99 & 100, are very difficult to recognize, because of the faintness of their light: one can observe them only in good weather, & near their passage of the Meridian.

― Connaissance des Temps, 1781

Drawings, descriptions, and CCD photos are copyright Andrew Cooper unless otherwise noted, no usage without permission.

A complete list of credits and sources can be found on the about page