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    Re: Magnetic Variation (Declination) Calculator
    From: Gary LaPook
    Date: 2009 Aug 5, 02:25 -0700

    Which is why Air Force navigators use grid directions in polar
    navigation. Grid north is in the direction that the Greenwich meridian
    runs. You then use "grivation", the difference between grid north and
    magnetic north. Heading are maintained with the standard aircraft
    "directional gyro" which does NOT seek north it just maintains its
    orientation in inertial space.
    
    gl
    
    On Aug 5, 2:45�am, Greg Rudzinski  wrote:
    > �If a navigator walks around the magnetic pole(as apposed to the
    > geographic pole) then it is the gyro compass that holds steady while
    > declination/variation changes rapidly. Therefor when near the
    > geographic pole use the magnetic compass to stay on track and when
    > near the magnetic pole use the gyro compass to stay on track.
    >
    > On Aug 4, 4:36�pm, Greg Rudzinski  wrote:
    >
    > > Professor Manoj C. Nair of NOAA was kind enough to answer all my
    > > questions by email and he explained to me that due to the convergence
    > > of longitude at the geographic pole there will be large change in
    > > declination(variation) as you walk around the pole with compa
    > > hand but the compass needle will be steady and unchanged as it seeks
    > > the magnetic pole. A simple concept that I should have been aware of.
    >
    > > On Aug 4, 2:33�pm, Greg Rudzinski  wrote:
    >
    > > > Brad,
    >
    > > > Manoj C. Nair of NOAA University of Colorado responded to my email
    > > > reguarding the zero result for 90� of latitude and said that the
    > > > current program recognizes latitudes above 89.999 as undefined. The
    > > > zero result must be a default number. I noticed another program glitch
    > > > where 13� West declination was displayed as 167� East.
    >
    > > > Greg
    >
    > > > On Aug 4, 10:20�am, Brad Morris  wrote:
    >
    > > > > Hi Greg
    >
    > > > > I just entered the pole for a gee-wiz kind of exercise. �To my 
    surprise, it returned zero, so I tried a location close to the pole. �That 
    returned non-zero, indicating that the software has some sort of bug.
    >
    > > > > Since I have no way to verify any other result it may present to me, I 
    will distrust the data. �How many other lat long locations give 'bad' data? 
    �How would I know?
    >
    > > > > Should NOAA fix this? �Certainly. How silly of them to permit an entry 
    which provides erroneous results.
    >
    > > > > Do navigators depend exclusively on a compass within 366 feet of the 
    north pole? �I sure hope not...
    >
    > > > > Best Regards
    > > > > Brad
    >
    > > > > -----Original Message-----
    > > > > From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Greg Rudzinski
    > > > > Sent: Tuesday, August 04, 2009 1:03 PM
    > > > > To: NavList
    > > > > Subject: [NavList 9329] Re: Magnetic Variation (Declination) Calculator
    >
    > > > > Brad,
    >
    > > > > It looks like values above 89.998996� of latitude are all zero instead
    > > > > of 14� 24'W. Does NOAA need to correct this since it is only 366 ft
    > > > > from the pole?
    >
    > > > > Greg
    >
    > > > > "Confidentiality and Privilege Notice
    > > > > The information transmitted by this electronic mail (and any 
    attachments) is being sent by or on behalf of Tactronics; it is intended for 
    the exclusive use of the addressee named above and may constitute information 
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    >
    >
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