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Rotation period of comet Donati


COMET Donati, 1858VI, was a spectacular comet, famous for its coma with multiple haloes, seen, described, and measured by many observers using optical telescopes. The haloes were roughly parabolic envelopes with vertices towards the Sun forward from the tail axis and the ‘foci’ near the apparent nucleus of the comet. The envelopes appeared to be uniformly spaced radially from the nucleus. Because of the regularity and observed sharpness of these haloes, I assume here that they represent repetitive ejection of material from a single active area exposed successively to solar radiation as the solid cometary nucleus rotated1.

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    Winnecke, A. Mem. Acad. Imp. Sci. St Peteresbourg Ser. 7, 2, 15 (1859).

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    Schmidt, J. F. J. Astr. Nach. 59, 97 (1863).

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    Whipple, F. L. Bull. Am. astr. Soc. 9, 563 (1977).

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