We compare the simultaneous 2007 space-based MOST photometry and ground-based radial velocity observations of the F5 star Procyon .
We identify slow variations in the MOST data that are similar to those reported in the radial velocity ( RV ) time series , and confirm by comparison with the Sun that these variations are likely the signature of stellar activity .
The MOST power spectrum yields clear evidence for individual oscillation frequencies that match those found in the radial velocity data by .
We identify the same ridges due to modes of different spherical degree in both datasets , but are not able to confirm a definite ridge identification using the MOST data .
We measure the luminosity amplitude per radial mode A _ { l = 0 , phot } = 9.1 \pm 0.5 ppm .
Combined with the estimate for the RV data by this gives a mean amplitude ratio of A _ { l = 0 , phot } / A _ { l = 0 , RV } = 0.24 \pm 0.02 ppm cm ^ { -1 } s , considerably higher than expected from scaling relations but in reasonable agreement with theoretical models by .
We also compare the amplitude ratio as a function of frequency , and find that the maximum of the oscillation envelope is shifted to higher frequencies in photometry than in velocity .