Astronomical Latitude By measuring the zenith distance when star is at minimum, yields latitude Problems Rotation axis moves in space, precession nutation Given by International Astronomical Union (AU) precession nutation theory Rotation moves relative to crust 02/803 12540Lec04 Rotation axis movement Precession Nutation computed from Fourier Series of motions Largest term 9"with 18.6 year period Over 900 terms in series currently(see http://bowie.mitedu/tah/mhb2000/jb000165onlinepdf Declinations of stars given in catalogs Some almanacs give positions of"date meaning precession accounted for02/18/03 12.540 Lec 04 7 Astronomical Latitude – Rotation axis moves in space, precession nutation. Given by International Astronomical Union (IAU) precession nutation theory – Rotation moves relative to crust 02/18/03 12.540 Lec 04 8 Rotation axis movement http://bowie.mit.edu/~tah/mhb2000/JB000165_online.pdf) • By measuring the zenith distance when star is at minimum, yields latitude • Problems: • Precession Nutation computed from Fourier Series of motions • Largest term 9” with 18.6 year period • Over 900 terms in series currently (see • Declinations of stars given in catalogs • Some almanacs give positions of “date” meaning precession accounted for 4