The Nautical Almanac and Astronomical Ephemeris for the Year ... (Google eBook)

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order of the Lords Commissioners of the Admiralty, 1835 - Nautical almanacs
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Page 495 - Sun's mean motion in Right Ascension, and the interval between the departure of any meridian from the mean Sun and its succeeding return to it, is the duration of the mean solar day. Clocks and chronometers are adjusted to mean solar time ; so that a complete revolution (through 24 hours) of the hour hand of one of these machines should be performed in exactly the same interval as the revolution of the Earth on its axis with respect to the mean Sun. If the mean Sun could be observed on the meridian...
Page 516 - The hours and minutes of Right Ascension, and the degrees and minutes of Declination, are placed at the heads of the columns as constants, and belong equally to all the numbers below them. This arrangement has rendered it necessary, in numerous instances, to continue the seconds beyond 60, as the width of the page would not permit of otherwise indicating any change in the minutes. Thus, the apparent Right Ascension of 12 Can urn Venaticorum at page 484, on December 17, 1S50, is registered 12...
Page 468 - Year 1881 there will be two Eclipses of the Sun and two of the Moon, and a transit of Mercury across the Sun's disc.
Page 495 - Hence it is that astronomers, with a view of obtaining a convenient and uniform measure of time, have recourse to a mean solar day, the length of which is equal to the mean or average of all the apparent solar days in the year. An imaginary Sun, called the
Page 501 - The progressive motion of light, combined with the motion of the Earth in its orbit, causes the Sun to appear in a different position from that which he really occupies, the true position being always in advance of the apparent. The numbers in this column indicate, for...
Page 499 - Sidereal Time at Mean Noon is the angular distance of the first point of Aries, or the true vernal equinox, from the meridian, at the instant of mean noon : it is therefore the Right Ascension of the mean Sun, or the time shown by a sidereal clock at Greenwich, when the mean time clock indicates oh om o*.
Page 507 - Satellite is at some Distance from the Body of Jupiter, except near the Opposition of Jupiter to the Sun, when the Satellite approaches nearer to his Body.
Page 198 - TRANSITS OF THE SATELLITES AND THEIR SHADOWS OVER THE DISC OF THE PLANET. THE SATELLITES OF JUPITER are not visible this Month, JUPITER being too near to the SUN. From Mean For correcting the Places of the Fixed Stars. 0 Noon of Mean Time H CO January 1.
Page 516 - ... the Right Ascension : also, for Stars having North Declination, + signifies add, and subtract: but for Stars of South Declination, + denotes that the Variation is to be subtracted from, and that it is to be added to, the Declination.
Page 495 - ... day is the interval of time between the departure of any meridian from a heavenly body and its succeeding return to it, and derives its name from the body with which the motion of the meridian is compared. The interval between the departure and return of a meridian to the Sun is called a solar day ; in the case of the Moon, the interval is called a lunar day ; and in that of a Star, a sidereal day.

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