Items needed: The Nautical Almanac, Sight Reduction Tables (229 for your latitude), accurate time piece, plotting paper, scratch paper, pencil, dividers, and parallel rulers, and triangles. You can try this for the moon, stars, and planets but the sun will be of the body you use most. When applying this to the moon use the "Altitude Correction Tables for the Moon, found on the inside back cover of the Nautical Almanac, date, latitude and longitude (DR position). Take upper or lower (limb) of the sun for a one-time effort. To increase your chances of success with the sun, there is the chance of taking both upper and lower limb readings. This is fine, but keep the math calculations separate, as the main correction for the semidiameter of the sun is added for the lower limb and subtracted for the upper limb.) Determine height of eye above water.
Try to judge the instant at which the selected limb touches the horizon (when it appears in the case of a rising sun, or disappears when setting) and note the exact watch time. In the case of the moon to some degree, and the stars and planets, use binoculars to increase light-gathering ability and to improve the estimate of when the body touches the horizon. Use of this for stars and planets is limited to clear nights moonlight providing a clear horizon. At dawn and dusk, when these bodies become more visible than during the day, the light usually impairs your ability to pick up the bodies as they rise or be certain of when they set. There is the possibility of "bobbing" a limb of the moon or the planets and stars at any time during the night. The technique may be used for a selected body disappearing over the horizon to the west or one to appear in the east. For a disappearing body, a low position in the boat is best for an appearing body, position yourself as high as possible. Either way, by standing upright and stooping, it is possible for a few moments to make the body appear and disappear. As this occurs, note the time and judge your average height of eye to obtain the "dip" factor.
Since you have no readings, you cannot plot them. You cannot be entirely confident that the timing was correct and was not influenced by the motion of the vessel. Uncertainty of 20 seconds as to when the limb or the body actually appeared when rising, or disappeared when setting, produces an uncertainty of approximately five nautical miles in your calculated line of position (LOP). If you are without a sextant, accuracy of plus or minus five miles might be considered a success.
Even though no sextant was used, the calculations for producing the observed altitude (Ho) are the same. The difference is that the sextant altitude is zero, since the observation was made when the limb or body was, in effect, brought down to the horizon. Obviously, there is no sextant error correction. Therefore, the calculation is worked as follows:
1.Take observed reading (0-00.0) degree's
2.Subtract dip for height of eye found inside front cover of the Nautical Almanac.
3.The result is apparent altitude. (Ha)
4.From page A3 of the Nautical Almanac under "Sun," select the month and upper or lower limb correction. (Alt. Correction).
5.The result is the observed altitude of the sun. (Ho)
From this point on the calculation of GMT, GHA, LHA, assumed latitude and longitude and the use of the Nautical Almanac and PUB 229 are exactly the same as for the sun.
Ho = 0°30.1' HoMoTo
Hc = 0°26.4' CGA Coast Guard Academy
Int = 0°03.7' (towards)
