What are the three main categories of deep-sky objects found in the Messier Catalog?

Answer

Star clusters, nebulae, and galaxies

The objects contained within the catalog represent the brightest easily observable deep-sky targets and fall into these three primary classification types.

What are the three main categories of deep-sky objects found in the Messier Catalog?
astronomydeep-sky objectscelestial objectsCatalogcatalogueMessierCharles Messier