Testing the Accuracy of Coimbra Astronomical Observatory Solar Filament Historical Series (1929–1941)

The present work aims to validate the positions of solar filaments published in Annals Coimbra University Astronomical Observatory, currently Geophysical and Observatory Coimbra, corresponding years 1929 1941. Stonyhurst were obtained by an original method devised early 20th century that used a spherical calculator instrument, wood-made model Sun. We digital images spectroheliograms measure filaments, heliographic coordinates determined with routines implemented Python package Sunpy. correlation coefficients between both sets are positive highly significant. results at observatory data. conclude filament catalogues reliable can therefore be considered for future activity studies.