Fig. 1
Speckle-restored blue continuum image from HiFI observed at 08:50 UT on 2016 September 24. The two black arcs mark the penumbral sector PS discussed in Sect. 3. The arrow in the lower right corner points to solar-disk center DC. The black oval and the two parallel lines inside the PS indicate the elongated, dark umbral core and the penumbral gap, respectively, which are discussed in Sect. 3.
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