|| Starpath online classroom || Celestial Navigation Glossary || Glossary Index || Home ||

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

Side Error A sextant misalignment that affects the view through the telescope but not the measured height. Side error is present when the two mirrors (horizon and index) are not perpendicular to the arc of the sextant. On a traditional sextant with half-silvered horizon glass, this error causes the image to jump from one side of the glass to the other as you scan the object with the sextant set to 0° 0'. It will also cause a smooth horizon to split apart as you rock the sextant, which is a good way to detect a even a small side error independent of index error. On full-view sextants, side error shows up as a light blue smear to one side of a distant object with a light yellow smear to the other side when the sextant is set to 0°. Instruction manuals (or Bowditch) tells how to remove this error with the adjustment screws at the mirrors. See Index Correction, Bowditch, and Full-View Sextants.

[close window]