Complex sentence: Some astrologers do not even use the astrological signs at all (mostly Cosmobiologists and Uranian Astrologers/Hamburg School); therefore they do not take into account planetary rulerships and the essential dignities when interpreting an astrological chart.
Split into simpler sentences: Some astrologers do not even use the astrological signs at all (mostly Cosmobiologists and Uranian Astrologers/Hamburg School). Therefore they do not take into account planetary rulerships and the essential dignities when interpreting an astrological chart.