INDEX ERROR

the discrepancy between a true and a recorded reading, especially that of a sextant (an instrument which measures the angular distance between objects). The index error is normally given as plus or minus, according to whether the observed reading must b e increased or decreased. —Perception of Truth Approved Glossary (9 June 92)

the discrepancy (difference) between a true and a recorded reading, especially that of a sextant (an instrument which measures the angular distance between objects). It is normally given as plus or minus, according to whether the observed reading must be increased or de creased.the discrepancy between a true and a recorded reading, especially that of a sextant (an instrument which measures the angular distance between objects). The index error is normally given as plus or minus, according to whether the observed reading must be increased or decreased.the discrepancy between a true and a recorded reading, especially that of a sextant (an instrument which measures the angular distance between objects). The index error is normally given as plus or minus, according to whether the observed reading must be increased or decreased. "You always know the index error of your sextant."