Delta Cephei is also of particular importance as a calibrator of the Cepheid period-luminosity relation since its distance is among the most precisely established for a Cepheid , thanks in part to its membership in a star cluster and the availability of precise Hubble Space Telescope\/Hipparcos parallaxes .
Delta Cephei is of great importance because its distance is extremely well known , thanks in part to it being in a star cluster , and the precise Hubble Space Telescope\/Hipparcos parallaxes .