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Fig. 4

image

Upper panel: Hα spectrum of the prominence observed on 18 May 2011 by the SLS spectrograph. The bright solar disc with the Hα line in absorption and many other absorption lines is clearly distinguishable in the upper part of the image. Below the disc, fainter emission of the prominence in Hα is visible. Bottom panel: observed Hα profile from the position along the slit indicated by the white horizontal dashed line in the upper panel. Spectral intensities of the profile are marked with the “+” symbols. Errors in spectral intensities were derived from counts in raw spectra using Poisson statistics. The observed profile is fitted with synthetic profile calculated by a simple cloud model. The synthetic profile is plotted with the solid line.

This figure is made of several images, please see below:

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