18 May
2009
18 May
'09
9:25 p.m.
Daniel is correct. Hipparchos' accuracy was about 0.001 arc-second, so if a system displayed less paralactic shift or orbital motion than that during the data-taking phase, it's motions remained unresolved. I dug out the Millenium Star Atlas and no proper motion data or distance is even indicated for Beta Cygni. Orbital parameters are beyond the purview of the Atlas. Erik, you maintain that it's a physical pair, but currently only a handful of states recognize that officially, and Utah isn't likely to be one of them anytime soon... ;o)