Sunspot number


Sunspot Number is calculated by using a formula devised by Rudolph Wolf in 1848:

R=k (10g+s),

where R is the sunspot number; g is the number of sunspot groups on the solar disk; s is the total number of individual spots in all the groups; and k is a variable scaling factor (usually <1) that accounts for observing conditions and the type of telescope (binoculars, space telescopes, etc.).

<AUR>.Report will provide a real observed number of spots and regions on the left sidebar and Sunspot Number calculated as above.