Saturday 11 June 2022

Partial Lunar Eclipse of 1892 seen with a Cooke


The Partial Lunar Eclipse of May 11-12, 1892. By G. J. NEWBEGIN, F.R.A.S.

The night of May 11-12 turned out so exceptionally clear and fine that (though in 16 ° of Declination) the moon soon became a steady object in the telescope. With regard to the eclipse I decided to take a series of photographs at about half-hour intervals, and to endeavour to secure a permanent record of its several stages. The exposures were made at 9.20, 9.50, 10.30, 11, 11.30 p.m., 12 o'clock midnight, and 12.30 a.m. The periods of exposure were varied, to allow for the decreasing illumination of the moon, viz. :— 20s 20s 30s 40s 30s 20s 20s respectively.

The plates were the Ilford ordinary, developed by hydroquinone. The instrument by which they were taken is a 9-inch Cooke equatorial, aperture reduced to 2-inch for the whole series. The intervals between the exposures were occupied in developing the plates.

Thorpe, Norwich, Nov. 11, 1892.

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