How accurately are the distances to the Encyclopedia stars known?
Except for Xi Ursae Majoris, all the stars in the Encyclopedia are in the Hipparcos catalogue. The typical error on Hipparcos parallaxes is 1 milliarcsecond, whereas the most distant stars in the Encyclopedia have parallaxes of 65 milliarcseconds. Thus, the relative uncertainty for the furthest stars is 1 / 65 = 1.5 percent. Most of the stars in the Encyclopedia are considerably closer, and have errors well under 1 percent. Xi Ursae Majoris is only in the Gliese catalog, which gives an error of 13 milliarcseconds in its parallax, corresponding to a relative uncertainty of 13.5% in its distance.
