The official SESC sunspot number is computed
according to the Wolf Sunspot Number formula R = k(10g + s),
where g is the number of sunspot groups (regions), s
is the total number of individual spots in all the groups and
k is a scaling factor that corrects for seeing conditions.
A sunspot number of zero indicates
there were no visible sunspots on that date; a blank indicates
that no observations were possible that day.
The sunspot region information used to
compute the daily sunspot number incorporates reports from as
many as six observatories. These reports are used to form a composite
picture of each individual region, taking into account such factors
as the time of observation and the quality of seeing.
