Statistics of the logarithmic flare index

We point out that the logarithm of the daily flare index, rather than the index itself, over a time intervall, is normally distributed. This enables us, by means of a random normal generator, to fill in values on ‘blank’ days when the flare activity is below the report threshold. In this way, an unbroken series of the logarithmic flare index was constructed for the Solar Rotations 1642–1684. The mean and s.d. in each rotation were then calculated and tabulated. These were found to be closely correlated with the mean and s.d. of the solar radio flux at 2800 MHz for the same rotations.