A Manual of Field Astronomy |
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Common terms and phrases
accurately American Ephemeris American Nautical Almanac approximate astronomical triangle azimuth mark AZIMUTH OF POLARIS Cassiopeia celestial equator celestial sphere Change circumpolar star computations and field-notes Computations Following Field Computations Preceding Field Compute azimuth convenient Corr earth Ephemeris and Nautical equation field astronomy formula given on pages Greenwich mean noon horizontal axis horizontal cross-hair hour angle hour circle limb line of sight local mean longitude mean azimuth mean solar mean sun measured altitude measured angle Meridian Altitude minute of arc observation consists observations for azimuth Outline of Observation parallax parallax correction plane polar axis Polaris previous observation refraction correction right ascension semi-diameter sextant solar attachment solar telescope spherical triangle star at elongation station subtract sun's center Table tangent screw telescope direct telescope inverted tion transit telescope vation is given vernal equinox vertical arc vertical circle vertical cross-hair Washington watch correction watch readings
Popular passages
Page 103 - The above table was computed with mean declination of Polaris for each year. A more accurate result will be had by applying to the tabular values the following correction, which depends on the difference of the mean and the apparent place of the star. The deduced azimuth will in general be correct within o'.3.
Page 99 - ADD to the tabular quantities four minutes for every degree of longitude the place is west of the standard meridian, and SUBTRACT when the place is east of the standard meridian.
Page 28 - Remittances should be made to the Superintendent of Documents, Government Printing Office, Washington, DC, by postal money order, express order or New York draft. If currency is sent, it will be at sender's risk. Postage stamps, defaced or worn coins, foreign coins and uncertified checks will not be accepted.
Page 99 - ADD to the time of west elongation om.io for every degree south of 40° and SUBTRACT from the time of west elongation om.i6 for every degree north of 40°. Reverse these operations for correcting times of east elongation.
Page 99 - SUBTRACT from the time of west elongation om. 16 for every degree north of 40°. Reverse these operations for correcting times of east elongation. E. To refer to any other than the tabular longitude: ADD om.
Page 99 - ... to 24 hours. Consequently an astronomical time less than twelve hours refers to the same civil day, whereas an astronomical time greater than twelve hours refers to the morning of the next civil day. It will be noticed that for the tabular year two eastern elongations occur on January 14 and two western elongations on July 13. There are also two upper culminations on April 14 and two lower culminations on October 14. The lower culmination either follows or precedes the upper culmination by i...
Page 17 - Mean Solar Day is the interval between two successive transits of the mean sun over the same meridian ; it begins when the mean sun is on the meridian.
Page 21 - The sidereal day is the interval between two successive upper transits of the vernal equinox over the same meridian.
Page 40 - We have already seen that when a ray of light passes from one medium to another of different density...
Page 28 - States, Alaska, Guam, Hawaii, Philippine Islands, Porto Rico, Samoa, or to Canada, Cuba, Mexico, or Shanghai. To other countries the regular rate of postage is charged, and remittances must cover such postage.