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Table 1

Line parameters.

No. Ion λ [nm] Height umbra [km] Height QS [km]

1 Fe i 396.55 5583  ~2501
2 Fe i 396.61 5683 4501
3 Fe i 396.93 5883 6001

4 Ca ii 396.85  ~10003  ~10001
5 Si i 1082.71 30023 5402
6 He i 1083.03  >10003

Notes. Line formation heights in the umbra and quiet Sun (QS) are taken from and

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