Sextant GHA Azimut Limbe Culmination Achernar Zn Alizés Dip Ho Fix Méridienne Crépuscule nautique Polaris Sirius Hauteur observée Traversée Erre Estime Déclinaison LHA SHA Aldébaran Canopus Capella Vega Arcturus Horizon Réfraction Semi-diamètre Intercept Sextant GHA Azimut Limbe Culmination Achernar Zn Alizés Dip Ho Fix Méridienne Crépuscule nautique Polaris Sirius Hauteur observée Traversée Erre Estime Déclinaison LHA SHA Aldébaran Canopus Capella Vega Arcturus Horizon Réfraction Semi-diamètre Intercept

Method and tables

FR

What are HO 249 sight reduction tables?

HO 249 is a set of tables that solves the spherical navigation triangle. By entering with the assumed latitude, LHA and the body's declination, you directly obtain the computed altitude (Hc) and azimuth (Zn). It's the standard method in Canada (Sailing Canada / TC) and the UK (AP 3270 = HO 249 under the RYA name).