Galactic Rotation period ...

https://sites.google.com/view/abraham-c/galactic/rotation

See also ...

Found, Galactic year

https://sites.google.com/view/abraham-c/found/galactic-year

220.109.712,5          years. File 28.242

222.254.000            years. File 27.090

233.050.855,4          years. File 26.969 

240.561.989,5          years. File 27.797

269.173,55 * 1.000     years. File 27.737