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 » Online Classroom   » Celestial Navigation   » Public Discussion of Cel Nav   » Sight Reduction tables Z value discrepancy

Author Topic: Sight Reduction tables Z value discrepancy
 eutectic77 posted December 11, 2020 08:12 AM                   I have come across what looks like a discrepancy in the Z value between the “Declination (0°-14°) Same Name Latitude” table in the class textbook and “Pub. 249 Vol. 3 Sight Reduction” table from the link “Celnav Course Material page” from Quiz CN07 and I’m not sure if I’m looking at this right. I came across this while working “7.4 Altair Sight Exercise, Star #3”. For a-lat = 45°N, Dec=N8°, LHA=305°Box 5 tab Hc (textbook) = 30° 00’ +45 111°Box 5 tab Hc (online link to Pub 249). = 30° 00’ +45 110°Shouldn’t these tables have the same values?Thank you
 David Burch posted December 11, 2020 10:40 AM                   I believe this is a rounding error from one year to the next in the computations.see this earlier notehttps://www.starpath.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=4;t=001186#000004 From: Starpath, Seattle, WA
 eutectic77 posted December 11, 2020 11:54 AM                   Great, the link you provided explained this situation well. The resulting rounding difference is an insignificant factor in our Zn calculations and the Z value could be slightly different, because of rounding, depending on the publication source used for sight reduction.

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