Beta Lyrae (HD 174638) is ascribed visual magnitude 30.0 in the Henry Draper catalog. There are hundreds of other stars in the catalog also given magnitude 30.0. What was meant by these nominal magnitudes? Is there a resource in Vizier or elsewhere that provides corrected magnitudes?
I have a problem to believe, that the visual magnitude of beta lyrae changes from 3.51 to 30 mags. Maybe 3.0 mag. I looked into the new Gaia catalogue and I am wondering about a lot of measurements. In most cases you can read N unbelievable values for one astronomical star and so on. In my opinion the Hipparcos and Tess catalogue conform better to terrestrial measurements until 2010.