In BUMP OF CHICKEN’s song 天体観測 (also the title of this episode), the singer sings about how in his obsession with looking at the stars, he overlooks the girl on Earth next to him. I guess this is kinda like that.
Also, about star magnitudes. Apparently stars are sometimes categorized by their brightness into categories with numbers. It’s a log scale, though, so it’s not like Vega is cheating to be magnitude zero. In fact, the scale they’re probably using is calibrated using Vega to be zero.
Episode 05: Torrent