# The American Ephemeris and Nautical Almanac

1968 includes separately paged supplement: The introduction of the IAU system of astronomical constants into the Astronomical ephemeris and into the American ephemeris and nautical almanac.

### Contents

 Illuminated disks of Mercury and Venus 304 SATELLITES 320 RISINGS SETTINGS AND MISCELLANEOUS TABLES 376
 Table 447 EXPLANATION 476 450 517

### Popular passages

Page iv - Universal and Sidereal Times, the ephemerides of the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, the geocentric ephemerides of Ceres, Pallas, Juno, Vesta, and Pluto, the nutation in longitude and obliquity, the Day Numbers, and the Phenomena, are prepared in HM Nautical Almanac Office.
Page 504 - The longitude of the evening terminator differs by 180° from that of the morning terminator. The position angle of the axis is the angle that the lunar meridian through the apparent central point of the disk towards the north lunar pole forms with the declination circle through the central point, reckoned eastward from the north point of the disk. The column headed Position Angle—Bright Limb contains the position angles of the midpoint of the illuminated limb, reckoned eastward from the north...
Page 504 - X is taken equal to the ratio of the illuminated portion of the apparent disk to the area of the entire disk regarded as circular.
Page 493 - the times at which the excess of the apparent longitude of the moon over the apparent longitude of the sun is 0°, 90°, 180°, and 270°, respectively.
Page 480 - Law, nV = k'(l + m), the semimajor axis a of an elliptical orbit must be expressed in order that the numerical value of the Gaussian constant, k, may be exactly 0.01720209895 when the unit of time is the ephemeris day. In astronomical units, the mean distance of the Earth from the Sun, calculated by Kepler's law from the observed mean motion n and adopted mass m, is 1.00000003.
Page 499 - ... the axis of the shadow and is positive toward the Moon. The tabular values of x and y are the coordinates, in units of the Earth's equatorial radius, of the intersection of the axis of the shadow with the fundamental plane. The direction of the axis of the shadow is specified by the declination d and hour angle n of the point on the celestial sphere toward which the axis is directed. The radius of the umbral cone is regarded as positive for an annular eclipse and negative for a total eclipse....
Page 477 - The ephemeris time at any instant is obtained from observation by directly comparing observed positions of the sun, moon, and planets with gravitational ephemerides of their coordinates; observations of the moon are the most effective and expeditious for this purpose. An accurate determination, however, requires observations over a more or less extended period; in practice, it takes the form of determining the time correction...
Page 480 - ¿2(1 + m), the semimajor axis a of an elliptical orbit must be expressed in order that the numerical value of the Gaussian constant k may be exactly 0.01720209895 when the unit of time is the ephemeris day. In astronomical units, the mean distance of the earth from the sun, calculated by the Kepler law from the observed mean motion n and adopted mass m, is 1.00000003.
Page 504 - The POSITION ANGLE of the AXIS is the angle that the lunar meridian through the apparent central point of the disk towards the north lunar pole forms with the hour circle through the central point, reckoned eastward from the north point of the disk. The POSITION ANGLE of the BRIGHT LIMB is the angle measured eastward from the north point of the disk to the midpoint of the illuminated limb.
Page iv - Contains the ephemeris of Universal and Sidereal Times, the ephemerides of the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, the geocentric ephemerides of Ceres, Pallas, Juno, Vesta and Pluto, the nutation in longitude and obliquity, the Day Numbers, and the Phenomena. This volume also contains data on mean places of stars; eclipses of the Sun and Moon; ephemerides for physical observations of the Sun, Moon, and planets; ephemerides of the satellites of Mars, Saturn, Uranus,...