They are the great nebula in Orion, and the star cluster in Hercules.
The star cluster 4681 is a fine sight with our largest glass.
No one has ever succeeded in measuring the parallax of a nebula or star cluster.
The star cluster 4608 is small, yet, on a moonless night, worth a glance with the five-inch.
The star cluster 4400 is about one quarter as broad as the moon, and easily seen with our smallest aperture.
Star cluster No. 4440 is a striking object, its stars ranging from the ninth down to the twelfth magnitude.
He put the instrument down and zeroed it on Messier 44, the Beehive star cluster in the constellation Cancer.
The illustrious astronomer saw on one occasion this object pass over a star cluster.
The most striking type of star cluster is well exhibited in the constellation of Hercules.
His eyes wandered from star cluster to star cluster, from glowing Regulus, to bright and powerful Sirius.