  Specola Solare Ticinese is an observatory dedicated to Sunspot Number
counting, which was constructed in 1957 in Locarno, Southern Switzerland, as an
external observing station of the Zurich Federal Observatory. When in 1981 the
responsibility of the determination of the International Sunspot Number was
assumed by the Royal Observatory of Belgium, Specola Solare Ticinese was given
the role of pilot station, with the aim of preserving the continuity in the
counting method. We report the observing procedure and counting rules applied
in Locarno.
