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» Online Classroom   »   » Public Discussion of Cel Nav   » calculating Hc

   
Author Topic: calculating Hc
David


 - posted May 16, 2017 01:32 PM      Profile for David           Edit/Delete Post 
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 , 2017
UT= 22 08 49
DR Lat=44 0.7
Lon= 92 31.3
AP Lat= 44
Long= 92 7.1

Using Nautical Almanac and Sight Reduction Tables, I obtain an HC of 33 09
But,
Using “USNO celestial Navigation Data for Assumed Position and Time.”, I obtain an HC of 33 57.1

My Ho=34 13.6

Can 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 Tables

I 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      Profile for David           Edit/Delete Post 
Belay my question dated 5/16/2017.....I found the error I was making
David

From: Minnesota


All times are Pacific  
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