Solar Physics

, Volume 291, Issue 9–10, pp 3075–3080 | Cite as

Sunspot Observations and Counting at Specola Solare Ticinese in Locarno Since 1957

  • Sergio Cortesi
  • Marco Cagnotti
  • Michele Bianda
  • Renzo Ramelli
  • Andrea Manna
Sunspot Number Recalibration

Abstract

Specola Solare Ticinese is an observatory dedicated to sunspot number counting. It was constructed in 1957 in Locarno, Southern Switzerland, as an external observing station of the Zurich Federal Observatory. When the responsibility of the determination of the International Sunspot Number was assumed by the Royal Observatory of Belgium in 1981, 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.

Keywords

Sunspots, statistics Solar Cycle, observations 

Notes

Acknowledgements

The association ASST organizes the financing of Specola Solare Ticinese and was established by Alessandro Rima (who directed it from 1980 until 1991) and Paul Utermohlen. Jan Olof Stenflo at ETHZ recommended using Specola Solare Ticinese as the pilot station for SIDC in Brussels. Since 1992, ASST has been directed by Philippe Jetzer. Specola Solare Ticinese is mainly financed by the Ticino Canton through the Swisslos found. We thank Mario Gatti for helpful discussions.

Disclosure of Potential Conflicts of Interest

The authors declare that they have no conflicts of interest.

References

  1. Clette, F., Svalgaard, L., Vaquero, J.M., Cliver, E.W.: 2014, Revisiting the sunspot number. A 400-year perspective on the Solar Cycle. Space Sci. Rev. 186, 35.  DOI. ADSCrossRefGoogle Scholar
  2. Stenflo, J.: 2016, Transition of the sunspot number from Zurich to Brussels in 1980: A personal perspective. Solar Phys.  DOI. Google Scholar
  3. Svalgaard, L., Cagnotti, M., Cortesi, S.: 2016, The effect of sunspot weighting. Solar Phys. (submitted). Google Scholar
  4. Waldmeier, M.: 1947, Heliographische Karten der Photosphäre für das Jahr 1946. Publikationen der Eidgenössische Sternwarte Zürich 9, 1. Google Scholar
  5. Waldmeier, M.: 1948, 100 Jahre Sonnenfleckenstatistik. Astron. Mitteil. Eidgn. Sternw. Zürich 152. Google Scholar
  6. Waldmeier, M.: 1968, Die Beziehung zwischen der Sonnenflecken-relativ-zahl und der Gruppenzahl. Astron. Mitteil. Eidgn. Sternw. Zürich 285. Google Scholar
  7. Wolf, R.: 1851, Sonnenflecken Beobachtungen in der zweiten Hälfte des Jahres 1850. Mitt. Nat.forsch. Ges. Bern 207, 89. Google Scholar
  8. Wolf, R.: 1856, Mitteilungen über die Sonnenflecken. Astron. Mitteil. Eidgn. Sternw. Zürich 1, 3. ADSGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • Sergio Cortesi
    • 1
  • Marco Cagnotti
    • 1
  • Michele Bianda
    • 2
  • Renzo Ramelli
    • 2
  • Andrea Manna
    • 1
  1. 1.Specola Solare TicineseLocarnoSwitzerland
  2. 2.Istituto Ricerche Solari LocarnoLocarno-MontiSwitzerland

Personalised recommendations