An Etymological Dictionary of Astronomy and Astrophysics
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Same as → Wolf number and → sunspot number.

→ relative; → sunspot; → number.

An average of 13 monthly → sunspot numbers, centered on the month of concern. The 1st and 13th months are given a weight of 0.5.

→ smooth; → sunspot; → number.

A quantity which gives the number of sunspots at a given time. It is defined by the relationship R = k(10g + f), where R is the sunspot number, k is a constant depending on the observation conditions and the instrument used, g is the number of the groups and f is the number of individual spots that can be counted. Also called the → Wolf number and → relative sunspot number.

→ sunspot; → number.