M15

M15 refers to a variety of things, most notably a type of rifle ammunition and a star cluster. As M15 ammunition, it is a 15-round cartridge, often used in handguns. It is typically a .22 caliber round, though variations exist. Its primary use is for hunting small game or for recreational shooting.

The M15 star cluster, also known as Messier 15 or NGC 7078, is a prominent globular cluster located in the constellation Pegasus. It is one of the most densely populated globular clusters known, containing an estimated 100,000 stars. M15 is located approximately 35,000 light-years away from Earth and can be observed with binoculars or a small telescope as a fuzzy patch of light. It is a popular target for amateur astronomers due to its brightness and accessibility. The cluster is believed to be about 12 billion years old and is notable for containing a planetary nebula and an unusual number of millisecond pulsars.