The Galactic Cepheids as observed from the Sun, with the Galaxy seen face on. The Sun is positioned at (x,y) = (− 8,0) kpc, and the Galactic center at (0, 0). The upper left panel shows the Berdnikov sample, and the other five panels show the synthetic Cepheid population divided into different G magnitude bins. The Cepheids in the lower right panel and those brighter than G = 6 would not be observed by Gaia.