To determine the Absolute Magnitude (MV), essentially the luminosity, of a Cepheid: first find the Period of the Cepheid along the horizontal axis (x-axis), go up to the diagonal line which corresponds to the Period-Luminosity relation, then read across to the vertical axis (y-axis) to see what value of MV it corresponds to. Write the corresponding value of MV in the correct column on your Cepheid Data Sheet.
