Spherical Astronomy

aberration according altitude apparent place arithmetical mean ascension and declination axes azimuth Bessel celestial sphere centre co-ordinates collimation compute correction cos & cos cos & sin cosine cotang deduced denote determined Diff difference of longitude differential coefficients dt dt earth easily ecliptic equal errors of observation expressed following equation formulae given hence horizon hour angle instrument intersects interval latitude logarithms meridian method moon multiply nutation obliquity obtain orbit order to find parallax plane pole precession probable error probable values proper motion radius refraction right ascension screw semi-major axis sidereal sine spherical substitute subtract tables tang telescope tion triangle true unknown quantities vernal equinox vertical circle wire zenith distance zero αβ