Mazumder, Rakesh; Chatterjee, Subhamoy; Nandy, Dibyendu; Banerjee, D
(IOP Publishing, 2021-10-01)
Hand-drawn synoptic maps from the Meudon Observatory (1919 onwards) and the McIntosh archive (1967
onwards) are two important sources of long-term, manually recorded filament observations. In this study, we
calibrate the ...