The World Data Center SILSO has adopted an open data policy and our sunspot data can be freely downloaded (Licence: CC BY-NC : https://creativecommons.org/licenses/by-nc/4.0). However, we kindly request that proper credit to the WDC-SILSO is explicitely included in any publication using our data (paper article or book, on-line Web content, etc.).
We suggest as minimum short-format credit : "Source: WDC-SILSO, Royal Observatory of Belgium, Brussels".
or "Sunspot data from the World Data Center SILSO, Royal Observatory of Belgium, Brussels".
In science papers, the source of data should be explicitly mentioned and referred to in the main text or figure captions. We recommend that you include an entry in the list of references, as follows:
SILSO, World Data Center - Sunspot Number and Long-term Solar Observations, Royal Observatory of Belgium, on-line Sunspot Number catalogue: http://www.sidc.be/SILSO/, ‘year(s)-of-data’
The Bibtex entry for this reference (Note: yyyy1 and yyyy2 should be changed respectively into the first and last year of the SIDC-data you have used):
@ARTICLE{sidc,
author = {{SILSO World Data Center}},
address = {Royal Observatory of Belgium, avenue Circulaire 3, 1180 Brussels, Belgium}
title = "{The International Sunspot Number}",
journal = {International Sunspot Number Monthly Bulletin and online catalogue},
year = yyyy1-yyyy2,
month = ,
volume = ,
pages = {},
adsurl = {http://www.sidc.be/silso/,},
adsnote = {}
}.
