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Sight Reduction The book and paper work of celestial navigation. It is the intermediate step to finding a fix from celestial sights; the first step is the sight itself, the last step is plotting the lines of position. Using Starpath workforms, sight reduction begins in Workform, Box 1 with the sextant height (Hs) and watch time (WT) of a particular sight. Using the Nautical Almanac and sight reduction tables, it ends with the four numbers in Workform, Box 6 (a-Lat, a-Lon, Zn, and a-value) that are used to plot the line of position. Once the procedures and workforms are familiar, the process takes about 15 minutes using tables. The same process can be completed with a programmed calculator in about 1 minute. In either case, the key to good sight reduction is to double check yourself at each stage. Blunders will usually stand out, but not until near the end of the process. See Workforms, Calculators, Nautical Almanac, and Sight Reduction Tables.

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