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Author Topic: calculating Hc
 David posted May 16, 2017 01:32 PM                   When calculating Hc using data from the Nautical Almanac and Sight Reduction Tables I am further from the Ho than if I input the raw data into “USNO celestial Navigation Data for Assumed Position and Time.” If I use an assumed longitude closest to my DR longitude the result is not as good as if I use an assumed longitude rounded to the next highest degree of longitude.For example, using the following data:Date: May 14 , 2017UT= 22 08 49DR Lat=44 0.7 Lon= 92 31.3AP Lat= 44 Long= 92 7.1Using Nautical Almanac and Sight Reduction Tables, I obtain an HC of 33 09But,Using “USNO celestial Navigation Data for Assumed Position and Time.”, I obtain an HC of 33 57.1My Ho=34 13.6Can you figure out why this is so? I believe I am using the correct assumed longitude. I did note that if I use an assumed longitude of 93 7.1 I get an Hc much closer to my Ho using the Nautical Almanac and Sight Reduction TablesI appreciate your help. Your book is great. I bought an additional copy for a friend of mine.David Driscoll From: Minnesota
 David posted May 17, 2017 06:16 AM                   Belay my question dated 5/16/2017.....I found the error I was makingDavid From: Minnesota

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