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    Re: Evaluation of H.O. 218
    From: Gary LaPook
    Date: 2011 Mar 15, 00:30 -0700

    I have attached the latitude 30°, declination 19° pages of H.O. 214 and the refraction correction page from the Nautical Almanac so that you can do your own analysis of the accuracy of H.O. 218. H.O. 218 includes the refraction correction added to its tabulations based on the refraction at 5,000 above sea level. Since the refraction at this height is about 85% of the refraction at sea level, the difference is negligible. So add the refraction correction from the Nautical Almanac to the tabulated values in H.O. 214 and compare them with the values in H.O. 218, they should be the same when rounded to a one minute of arc accuracy.

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