Sunspot-group nesting statistics and longitude-time diagrams from RGO and KMAS datasets (1874-2025)

Description

This dataset supports the quantitative analysis of sunspot group nesting, which is the tendency of solar active regions to emerge repeatedly in the same longitude-latitude zone over the course of a solar cycle. It contains processed sunspot group emergence records from two major observational catalogs, the Royal Greenwich Observatory Photoheliographic Results (RGO, 1874–1976) and the Kislovodsk Mountain Astronomical Station (KMAS, 1955–2025), together covering 14 solar cycles. Each record corresponds to the first appearance of a sunspot group on the solar disc, with its Carrington longitude, heliographic latitude, and maximum observed area in the course of its later evolution. Using these data, nesting was identified and quantified via a Kernel Density Estimation (KDE) informed DBSCAN clustering algorithm applied to the longitude-time plane in 5-degree latitude bands, separately for each solar cycle and hemisphere. The resulting nesting statistics (including nesting degree, number of significant nests, and characteristic nest separations) are provided as tabular data alongside longitude-time diagrams illustrating the identified nesting patterns. The dataset enables reproducibility of the results in the associated publication and facilitates comparison with future observational or modelling studies of solar magnetic flux emergence. See the README for details of the files provided.

Steps to reproduce

"Quantifying Sunspot Group Nesting with Density-Based Unsupervised Clustering", Solar Physics [vol/page] (2026) https://doi.org/10.1007/s11207-026-02632-2

Institutions

• Ankara University

  Ankara, Ankara
• Max Planck Innovation

  Bavaria, Munich

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