Equivalence Relations Between the Cortie and Zürich Sunspot Group Morphological Classifications
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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/).
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Conflict of Interest: The authors declare that they have no conflict of interest.
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