[amsat-bb] Re: Magnetic North vs True North
jlv at fing.edu.uy
Thu Sep 8 18:03:48 PDT 2011
That is true.
For my position
MONTEVIDEO - URUGUAY Latitude: 34° 54' 38.2" S
Longitude: 56° 11' 35.9" W
Magnetic declination: 9° 34' WEST
Declination is NEGATIVE
Inclination: -39° 37'
Magnetic field strength: 23116.9 nT
Jose Luis Vila
----- Original Message -----
From: "Edward R. Cole" <kl7uw at acsalaska.net>
To: "jlv" <jlv at fing.edu.uy>
Sent: Thursday, September 08, 2011 1:12 PM
Subject: Re: [amsat-bb] Re: Magnetic North vs True North
> At 07:30 AM 9/8/2011, you wrote:
>>Look for the magnetic north with the compass, read their geographical
>>coordinate in the GPS,
>>use this webpage
>>and calculate the magnetic declination for their place.
>>You will know where this the true north using the magnetic north + / - the
>>degrees of magnetic declination.
>>Jose Luis Vila
>>-----Mensaje original----- From: Luc Leblanc
>>Sent: Wednesday, September 07, 2011 10:07 AM
>>To: amsat-bb at amsat.org
>>Subject: [amsat-bb] Magnetic North vs True North
>>How i find my north!
>>At noon always using standard time i pointed the beam in the direction of
>>top tower pole shadow on the ground. Quite simple and accurate
>>Luc Leblanc VE2DWE
>>DSTAR urcall VE2DWE
>>WAC BASIC CW PHONE SATELLITE
> thanks Jose,
> very useful as declination is moving +17min/year here
> 17deg52min east
> I have old aviation maps of the region showing 26-deg declination.
> The sun shadow method works only if you know accurately what time solar
> noon is. For our time zone it is 2202:52 utc (today) which corresponds to
> 2:02:52 pm local time. So if you used the shadow at 12:00:00 local time
> you would be off considerably from true north. Of course one hour is due
> to daylight savings time which advances the clock one hour in summer and
> the fact that our local time was permanently advanced by one hour for
> political/business reasons (so we would only be +4 hours from EST in the
> This is the reason that one must know true north to orient a sundial.
> Sea navigators know they either need to know time precisely to "shoot the
> sun" and find their location or know true north to determine the exact
> time of meridian crossing at noon.
> 73, Ed - KL7UW, WD2XSH/45
> BP40IQ 500 KHz - 10-GHz www.kl7uw.com
> EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-60w, 3400-?
> DUBUS Magazine USA Rep dubususa at gmail.com
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