Observed to true altitude

When we take a sextant altitude of a heavenly body, we measure the angle between the body and the visible sea horizon as witnessed from the observer’s position on the bridge of a vessel. (angle DOX in the diagram). This is referred to as the observed altitude. In converting it…

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Introduction

Individual corrections. In order to be able to use the altitude obtained by sextant of a heavenly body, we need to convert it from a sextant altitude to a true altitude. To do this we need to apply five individual corrections to the altitude obtained from the sextant, namely corrections…

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