107 citations · 619 across the 28 of their papers we have counts for
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astro-ph.SR2017★ 39 cited
Analysis of full disc Ca II K spectroheliograms. I. Photometric calibration and CLV compensation
Theodosios Chatzistergos, Ilaria Ermolli, Sami K. Solanki +1
Historical Ca II K spectroheliograms (SHG) are unique in representing long-term variations of the solar chromospheric magnetic field. They usually suffer from numerous problems and…
astro-ph.SR2017★ 107 cited
New reconstruction of the sunspot group number since 1739 using the direct calibration and "backbone" methods
Theodosios Chatzistergos, Ilya G. Usoskin, Gennady A. Kovaltsov +2
Group sunspot number (GSN) series constitute the longest instrumental astronomical database providing information on solar activity. It is a compilation of observations by many ind…