General Weather/Earth Sciences Topics > Aviation Weather

To go True or Magnetic

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Randall Kayfes:
Just for kicks and I mean kicks - Polaris the North Star is Declination: +89 21' 42.44" So you can see that Polaris is about 18' from the Celestial North Pole which the earth's true north pole generally points to. Since Polaris is not on the Celestial Pole that means it circles it. So technically the Pole star aligns with the true north of the earth twice a day. Astronomers like me have to use Pole tables or programs to align our scopes with the celestial pole based on sighting and then offsetting Polaris. Also because of orbital and lunar considerations the true north pole of the earth can get ever so slightly out of alignment with the celestial pole as well. And Polaris is a double star, so which one do you use.

So, if you really want to be accurate...  :grin:   \:D/

(Just having fun - and remember don't trust atoms - they make up every little thing...)

davidmc36:

--- Quote from: ValentineWeather on November 03, 2015, 12:44:53 PM ---Well figured out why the station we moved yesterday anemometer wind direction was so far off. The phone app was off by 30+ degrees compared to real compass. Did several more calibrations with app twirling phone and it finally started agreeing with compass. Don't trust these apps on phones I guess. :sad: The reason I used it in first place, it had declination built-in when the gps is turned on.

--- End quote ---

Phone App. Ewwww! And the GPS will only help while moving.

If you have any desire to calibrate it to anything a 50 dollar compass can be a good piece of kit.

box:
 Mag variation in these parts is around 1degree west so to all intents and purposes can be ignored

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