SinnottRoger W., “PLANETS”: A computer program for positions and other data concerning the Sun, Moon, and planets; Apple II version (Cosmic Computer Works, 1980). This program calculates a variational orbit with elements generally improved over those used in Bryant Tuckerman's Planetary, lunar, and solar positions, 601 B.C. to A.D. 1649 (Philadelphia, 1962, 1964). All precise lunar and planetary positions and illuminations referred to in this article were calculated with “PLANETS”. The apparent positions are corrected for parallax and refraction.
2.
BaxendallDavid, “Replicas of two of Galileo's telescopes”. Transactions of the Optical Society of London, xxv (1922–23), 141–4. Baxendall gives the dimensions of the telescopes and lenses preserved at Florence, and translates brief accounts of G. Abetti of observations of Jupiter, Saturn, the Sun and the Moon made with the original telescopes in 1923.
3.
The replica uses a plano-convex objective 38mm in diameter, diaphrammed to 16mm, with a focal length of 1m. The eyepiece is a double-concave lens 19mm in diameter and −50mm focal length. These lenses were obtained from Edmund Scientific Co., 7785 Edscorp Building, Barrington, NJ 08007, U.S.A.
4.
RothG. D. (ed.), Astronomy: A handbook, transl. by BeerArthur (Cambridge, Mass., 1975), 362. W. Sander states that observations over several days must be compared to make the most accurate determination of the apparent dichotomy of Venus.
