English: M73, a small open cluster in the constellation Aquarius, is a minor though genuine Messier object, probably appearing just nebulous enough through Messier's early-generation telescope to qualify. It is a group of four bright stars with not much else around. Although some people think it is an asterism, that is, an accidental grouping on the sky of unrelated stars, others think it may be a genuine physical group, though sparse (in the extreme). Very little research has so far been devoted to settling this question. This picture was taken with the Kitt Peak 0.9-meter telescope in July 1997 during the Research Experiences for Undergraduates (REU) program operated at the Kitt Peak National Observatory and supported by the National Science Foundation.