Our Astronomical Column
1907; Nature Portfolio; Volume: 76; Issue: 1977 Linguagem: Inglês
10.1038/076526a0
ISSN1476-4687
Tópico(s)History and Developments in Astronomy
ResumoDANIEL'S COMET (1907d).—An excellent reproduction from a photograph, and a description of comet 1907d, are published in the September number (p. 385) of the Bullétin de la Société astronomique de France by M. F. Quénisset, of the Juvisy Observatory. With a clear sky, the comet appeared incomparaty bright than the Andromeda nebula, and gave the impression of being about the brightness of seacond magnitude star; the tail could be seen, by the naKed eye, extending to a distance of 8° or 10°. Between July 12 and August 15 twenty-six photographs were obtained, three portrait lenses of 16.0, 13.5, and 3.8 cm. aperture, and 0.740, 0.565, and 0.130 metre focal length, respectively, being chiefly employed. On these photographs the structure of the tail is very sharply defined, and on one obtained with the last-named objective the tail can be traced for, not less than 17°. From the photographs obtained with this instrument on August 7 and 8 there is evidence of a rotatory motion of the comet about a line joining the nucleus and the sun.
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