A Treatise on Practical Astronomy: As Applied to Geodesy and Navigation

accuracy altitude angle apparent approximation arithmetical mean ascension and declination axis azimuth Bessel catalogue celestial sphere centre chronograph chronometer circle circumpolar stars co-ordinates coefficients collimation computation constant convenient culmination derived determined difference differential dt dt earth east ecliptic elongation emersion employed ephemeris equal equatorial intervals example follows formulæ geocentric given gives Greenwich horizon hour-angle instant latitude limb logarithms longitude mean solar measured meridian method micrometer middle thread moon moon's right ascension multiplied Nautical Almanac obtained occultation parallax plane position prime vertical probable error proper motion reading reduced refraction right ascension screw semidiameter sextant sidereal sin² star's stars observed Substituting subtract telescope tion transit instrument unknown quantities values vernier weight write zenith distance