A determination of solar rotation using sunspot spectra

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Abstract
A spectroscopic determination of solar rotation is made at the centre of the (30 arcsec) umbra of a very large sunspot. Component velocities, rotation and vertical motion, are obtained from the shifts of molecular lines in the region of the atmospheric oxygen lines at λ 6300 Å. The rotational velocity component is equal(± 0.02 km/s) to the rotation rate obtained from recurrent sunspots; there is no detectable ( ± 0.09 km/s) vertical component.