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Calibrated sunspot area & PSI (Photometric Sunspot Index) data
Overview:
A cross-calibrated record of daily sunspot areas and the Photometric Sunspot Index (PSI) covering the years 1874 to 2025. It represents the most comprehensive catalog of sunspot areas to date, created by comparing records from nine different observatories and matching their sunspot data to develop a homogeneous catalog. Throughout this process, various statistical aspects were thoroughly examined and corrected as needed. This benchmark dataset is essential for robust long-term studies of solar cycles and the reconstruction of empirical solar irradiance, and it is now widely used in subsequent research.
Read more about the calibration procedure in the Astronomy & Astrophysics (A&A) paper @ https://doi.org/10.1051/0004-6361/202037547.
These catalogs are live and regularly updated to include new sunspot data.
aa37547-20.pdfDownload links (Google drive):
Sunspot area series from Kodaikanal Solar Observatory
Overview:
In 2017, I published the first catalog of sunspot areas, along with their positions, covering a 90-year period from 1921 to 2011. This data was obtained from newly digitized and calibrated white-light images from the Kodaikanal Observatory. The catalog was later extended to include data from 1901 to 1920 and from 2011 to 2017. This page provides links to download these datasets.
For more information about the original catalog, please refer to the paper by Mandal et al. (2017) @ https://doi.org/10.1051/0004-6361/201628651.
aa28651-16.pdf
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