RR Lyrae
Knowing the period-luminosity relation for local RR Lyrae-type variable stars allows the distance of more distant stars of this type to be determined. The distance of RR Lyrae remained uncertain until 2002 when the Hubble Space Telescope was used to fix its distance within a 5% margin of error. The result was . When combined with measurements from the Hipparcos satellite and other sources, the result is a distance estimate of .