Equivalence Relations Between the Cortie and Zürich Sunspot Group Morphological Classifications
- 93 Downloads
Catalogues of sunspots have been available with useful information about sunspots or sunspot groups for approximately the last 150 years. However, the task of merging these catalogues is not simple. We suggest a method of converting the types of sunspot groups that was proposed by Cortie (Astrophys. J. 13, 260, 1901) into the well-known Zürich types of sunspot groups. To achieve this, we used the sunspot catalogue of the Valencia University Observatory (from 1920 to 1928) in addition to the descriptions proposed by Cortie. To assess the quality of this conversion scheme, the Zürich type was computed from the Valencia catalogue, and the resulting contribution of each group type was compared to what can be found in other catalogues. The results show that the proposed scheme works well within the errors that are found in the different catalogues.
KeywordsSunspots Morphological classification of sunspots Cortie classification Zürich classification
Support from the Junta de Extremadura (Research Group Grant No. GR10131), from the Ministerio de Economía y Competitividad of the Spanish Government (AYA2011-25945), and from the COST Action ES1005 TOSCA ( www.tosca-cost.eu ) is gratefully acknowledged. L.L. acknowledges funding from the European Community’s Seventh Framework Programme (FP7-SPACE-2012-2) under Grant Agreement 313188 (SOLID project, projects.pmodwrc.ch/solid/).
Compliance with Ethical Standards
Conflict of Interest: The authors declare that they have no conflict of interest.
- Ananthakrishnan, R.: 1952, A note on the observations of sunspots recorded at Kodaikanal from 1903 to 1950, Kodaikanal Observatory Bulletin No: CSSSIII. Google Scholar
- Bray, R.J., Loughhead, R.E.: 1964, Sunspots, Dover, New York. Google Scholar
- Hale, G.E., Nicholson, S.B.: 1938, Magnetic Observations of Sunspot 1917 – 1924 498, Carnegie Inst., Washington. Google Scholar
- Observatorio de Valencia: 1928a, Publicaciones del Observatorio Astronómico, cuaderno no. 2, Valencia. Google Scholar
- Observatorio de Valencia: 1928b, Publicaciones del Observatorio Astronómico, cuaderno no. 3, Valencia. Google Scholar
- Waldmeier, M.: 1947, Publ. Zürich Obs. 9, 1. Google Scholar