Einiges zur Statistik der Radialbewegungen von Spiralnebeln und Kugelsternhaufen in Astronomiche Nachrichten 215, 349-354, 1921
Kiel: C. Schmidt, 1921. 1st Edition. FIRST EDITION OF WIRTZ’S 1921 STUDY OF THE BRIGHTNESS & DOPPLER SHIFT OF A NUMBER OF SPIRAL NEBULAE, HERE – 8 YEARS BEFORE HUBBLE -- PRESENTING THE FIRST SUGGESTION OF A LINEAR RELATIONSHIP BETWEEN VELOCITY AND APPARENT MAGNITUDE. In this paper, the title of..... More