Vega (aka Alpha Lyrae) is the brightest star in constellation Lyra. It is a relatively close star, 25 light-years from Earth, and one of the most luminous stars in the neighborhood, along with Arcturus and Sirius. It is very well studied and some of the first spectral measurements were done on Vega, and various Magnitude measurements were originally scaled to Vega being 0.
Absolute Magnitude (M)
Apparent Magnitude (m)