Why is magnitude of Beta Lyrae given as 30.0 in Henry Draper catalog?
30.0 mean &quot;variable&quot;.
If you click on the &quot;Ptm&quot; column header, you get a pop-up window including &quot;Note (2) : codes used for the magnitudes:&quot;; below that is a list of codes, including &quot;30.0 = variable (var. in published catalog)&quot;