## Longitude by Lunar Distances: Illustrated with Examples Worked Out Step by Step, and with References to Works on Practical Astronomy and to the "Nautical Almanac." |

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Longitude by Lunar Distances: Illustrated with Examples Worked Out Step by ... Henry Wilberforce Clarke No preview available - 2014 |

Longitude by Lunar Distances: Illustrated with Examples Worked Out Step by ... Henry Wilberforce Clarke No preview available - 2015 |

### Common terms and phrases

31st Dec 9th March Airy says altitude h altitude of moon's American Almanac apparent lunar distance approximate interval appt assumed longitude Astronomy azimuth calculation Captain Toynbee Challis Chauvenet chronometer computed cos2 Q cosec east and west equation equatorial horizontal parallax find the moon's Fomalhaut formula geocentric lunar distance geocentric zenith Greenwich mean hour angle instrumental errors latitude log A'+Q Log sin lunar dist lunar observations lunar star mean noon mean sun measured geocentric lunar moon Moon's augmented semi-diameter moon's centre Moon's equatorial horizontal Moon's geocentric declination Moon's geocentric semi-diameter moon's lower limb moon's semi-diameter N. P. distance Nautical Almanac Navigation normal centric parallax Observed altitude Observed lunar distance P.L. of diff Pegasi recorded lunar refraction Riddle Right Ascension sextant sidereal sin2 Spherical Trigonometry star lunars star's sun lunar sun's semi-diameter Tables XIX.a true geocentric true longitude vertical semi-diameter west lunars zenith distance

### Popular passages

Page 74 - Mean time of the Semidiameter passing may be found by subtracting 0-19 from the Sidereal Time.

Page 4 - This rule, with some modification, will answer for calculating the time of an occultation of a fixed star or planet by the moon. In this case the star's longitude is to be found in Table XXXVII.

Page 5 - The degree of accuracy with which sextant observations can be made, depend on the health of the observer. A clear head, a steady hand, a sharp eye, a calm mind, are necessary for success as an observer.

Page 7 - Pisces' (Bailey) ; ie when the apparent motion of a planet is contrary to that of the sun in the ecliptic. 51. disease : trouble, disquiet. Palsgrave,

Page 18 - ... PM is the local meridian, PG the Greenwich meridian, PS the hour circle through a star and PT the hour circle through the vernal equinox. Then GPT is the Greenwich sidereal time (GST) found from the chronometer regulated to keep Greenwich sidereal time. TPS is the star's right ascension (RA) found from the table of apparent places of stars in the Nautical Almanac.