Keplerian Rotation Curve of the Milky Way

Use is made from the data from the Gaia satellite of 2013, which measured the rotation of our galactic system by parallax measurements. This implies that the rotation velocities were measured directly without applying the Doppler effect. The results from Gaia allow for a new understanding of flat rotation curves of galactic systems. The study uses earlier findings that the IG/I measurements collected by CODATA show that the gravitational constant IG/I is not a universal constant of nature, but depends on the distance to the center of a mass. At a place where IG/I is larger, the inert mass of, for example, an electron will be larger. This leads to the concept of gravitational spectrum shift. It implies that the emitted spectrum of a star depends on its location within its galacticum. A different spectrum means a different redshift and that implies that the Doppler method for measuring the rotational velocities of stars generally provides wrong data. From available literature the Milky Way rotation curves for conditions with low as well as high accelerations are considered. The two different cases are the nearby solar region and a region far away from the galactic center. Within the solar region all spectra originate with the same IG/I value as near the Sun, and therefore the Doppler method can safely be used. This is different for the case far away from the galactic center, where the impact of the center of mass of the Milky Way on IG/I is small. The conclusions, which have been obtained by analyzing available data, lead to flat rotation curves with a Keplerian decline without introducing dark matter.