Sight reduction
![Correction to the sextant altitude](/Images/godic/202502/11/Corrections_for_Sextant_Altitude.en3719.jpg")
![Marcq St Hilaire intercept for the line of position](/Images/godic/202502/11/MarcqSaintHilaire.en3719.jpg")
![Haversine Sight Reduction algorithm](/Images/godic/202502/11/Haversine_Sight_Reduction3719.jpg")
![Azimuth diagram by Hanno Ix](/Images/godic/202502/11/Azimuth_diagram_by_Hanno_Ix3719.jpg")
Sight reduction, is the process of deriving from a sight the information needed for establishing a line of position.
Sight is defined as the observation of the altitude, and sometimes also the azimuth, of a celestial body for a line of position; or the data obtained by such observation.