JohnnyM.'s Astrolabe Geocoin
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Owner:
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JohnnyM.
Message this owner
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Released:
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Monday, February 2, 2009
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Origin:
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Czechia
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Recently Spotted:
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In the hands of the owner.
This is collectible.
Use TB2V1D6 to reference this item.
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To be in small collection of my owner.
I want to travel from event to event with my owner.
You can see me in the hands of JohnnyM. mostly stays in Prague (Czech Republic).
How to use me:
Taking a latitude reading from the North Star, Polaris:
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Grasping the ring, hold the astrolabe up in the air towards the North Star.
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Line up the holes in the spinning alidade so that you can see Polaris through them.
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Take the reading from the degree scale and you now have your latitude.
Measuring the declination of the sun:
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Grasping the top ring, hold the astrolabe to about chest high.
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Looking down on the alidade, let the sun shine directly though the upper alidade hole.
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Adjust the alidade so that the beam of sunlight shinning through the upper hole passes through the lower hole. The picture below shows how the light and shadow from the upper alidade look when slightly misaligned with the lower alidade hole.
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Now you can take a reading from the degree scale and see the declination of the sun. In this example, the degree scale shows the sun is at 11 degrees. These example photographs show the angle of the sun during the evening to give better contrast of the sunlight passing though the hole. When using the Mariner's Astrolabe Geocoin™ for navigation, you will want to take a reading at high noon.
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