Measurements of strong magnetic fields in umbra of sunspots: Crimea vs Mt. Wilson

TL;DR

This study compares magnetic field measurements of sunspot umbrae from Crimea and Mt. Wilson observatories, revealing significant discrepancies and analyzing their possible causes.

Contribution

It provides a comparative analysis of sunspot magnetic field measurements from two observatories over several years, highlighting measurement differences and potential reasons.

Findings

Average magnetic field: Crimea 2759 G, Mt. Wilson 2196 G

Maximum measured field at Mt. Wilson < 2.7 kG, Crimea > 4.0 kG

Correlation coefficient between observatories < 0.22

Abstract

The comparative analysis for 1324 measurements of the corresponding sunspot magnetic fields with B > 2.5 kG (according to Crimean data) obtained at Crimean and Mt. Wilson observatories from 2010 to 2017 has been carried out. It has been shown that the difference between measurements can exceed 1 kG in some cases. The averaged values of the magnetic field are equal to 2759 G (Crimea) and 2196 G (Mt. Wilson). The maximum sunspot magnetic field measured at Mt. Wilson does not reach 2.7 kG while according to Crimean data it can exceed 4.0 kG. The correlation coefficient between measurements of magnetic fields in different observatories does not exceed 0.22. The probable reasons of significant discrepancies are discussed.