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    Re: Sunset Intercepts
    From: Greg Rudzinski
    Date: 2012 Aug 2, 18:10 -0700

    The UT date of yesterdays sunset was 8/2/2012 not 8/1/2012

    [NavList] Sunset Intercepts
    From: Greg Rudzinski
    Date: 2 Aug 2012 17:58
    Yesterday's sunset emerged from a low ceiling at the very last minute to be photographed and timed on the horizon. There is something neat about using the horizon as a natural sextant. The sight reduction is not so neat since the calculated altitude and observed altitude are both negative. I am not much for the negative so at least the calculated altitude can be made positive by selecting an assumed position further west.

    Actual position
    Lat 34* 10.4' N
    Lon 119* 14.1' W

    Height of Eye 12 ft.

    hs 0* lower limb Sun
    dip -3.4'
    ref. S.D. -17.8'
    Ho -21.2' (Nautical Almanac)

    UT 02:55:07 8/1/2012
    GHA 222* 12.9'
    LHA 102* 58.8'
    Dec 17* 40.6'
    Hc - 22.3'

    Intercept 1.1 toward
    azimuth 291.8*

    If an assumed longitude of 120* 12.9' W is used in lieu of 119* 14.1' W then :

    LHA 102*
    Dec 17* 40.6'
    Lat 34*
    Hc 19.2'

    Intercept 40.4' away
    azimuth 291.3*

    For some having a positive calculated altitude might avoid some confusion on the sunset intercept determination.


    Greg Rudzinski

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