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post #14 of Old 04-09-2012
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Re: practicing with sextant on land

Hah, looking at some of the other tables available on milutin's link:

"Temperature and Pressure Factors for Refraction (Corrected Refraction = Tabulated Refraction x Factor". I like corrections on the corrections :P The take-home lesson seems to be, never shoot stars near the horizon. Above 2512', the correction is less than 2 minutes, and above 4533', the correction is less than 1 minute.

"Moon's Semi-Diameter Corrected for Augmentation", which is indexed by Alt and HP, followed by "Latitude Correction to Moon's HP". Awesome. You use your latitude to correct the tabulated HP, which you use to correct the moon's semi-diameter, which you use to correct your sextant altitude (which you use to calculate latitude!) Take-home lesson: the moon is not worth it.

That said I'm now getting excited to try the Lunar Distance method for calculating time. I guess I'll wait until the next first-quarter, though. One advantage is that it's sextant practice that doesn't require a horizon.

s/v Laelia - 1978 Pearson 365 ketch

Last edited by AdamLein; 04-09-2012 at 12:29 PM.
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