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Fig. 1.


Left: solar chromosphere in Hα at 656 nm. This cropped frame contains the top left quarter of the solar disk: approximately 810 × 810 arcsec; compare with the simultaneous image in Ca II on the right. The original image covers the full disk in 2k × 2k pixels. Images are taken every minute, from one hour after sunrise to one hour before sunset, weather allowing. Right: solar chromosphere in the Ca II line at 393.4 nm. These two images were taken with l1 and l2 at Pic du Midi (2015-03-27).

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