RR Lyrae Stars are a class of variable star which have a period of luminosity between 0.2 and 1 Day.
Another useful thing is that they all have the same period to absolute magnitude ratio, which means
by just measuring their brightness from earth, we can tell how far away they are since they are a type
of standard candle. They are usually too faint to be identified in far away galaxies, but they can be
observed with large telescopes in the Andromeda Galaxy, and much smaller telescopes in the Milky Way.
Globular Clusters are usually a hotspot for finding RR Lyrae variables, as I divulge below.
Turned out better than the faint M79 with the 14 incher. Look carefully and you can spot a few
RR Lyrae stars getting brighter and dimmer in this animation.
M79 was too distant and the seeing was too poor to reliably measure any RR Lyrae stars.