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Laymans terms needed badly...


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I've read it once, twice, three, four times, and this bit of information I so very much want to grasp, but it won't penetrate my grey matter..... :clouds2:  I don't understand Right ascension and Declination.

And then if(?) I do eventually understand it, how do I implement it in the night sky.

Any help would be greatly appreciated.

Caz  :sunny:

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OK. For once, this will be a perfectly serious answer. :clouds2:

You are standing on the earth, at about 52degrees North latitude. Imagine that the sky is a hollow globe, the interior of which is some distance above the earth (like, several light years.) The globe has the same north pole, south pole, and equator, as the globe you are standing on. The main difference is that the celestial globe does not rotate with the earth.

This celestial globe is divided into latitudes and longitudes, in exactly the way the earth's globe is. Celestial latitudes are measured in degrees, and are called declimation. Celestial longitudes, however, are measured in hours, minutes, and seconds. So, there are 24 hours in the full circle of the celestial equator. Anything at 52 degrees north on the celestial equator will pass over your head sometime in a 24 hour period.

So, this give you a coordinate system you can use to locate any object on the celestial globe, in exactly the same way I can give my location on Earth as 43 degrees north, 79 degrees west. If I were a star, I would be at 43 degrees north, 5h 16m RA approximately, and I would be fixed on the celestial sphere, while the Earth rotated on, and I would pass over the head of anyone in Niagara, once a day..

Given that information, if you know the declination and RA of the thing you are looking at, and the declination and RA of the next thing you want to look at, you can set your RA setting circle to the appropriate RA, and point your scope to the RA and declination of the new object.

0h passes between Cetus and Aquarius. I don't know why.

Again, seriously, most amateur astronomers find things using their star charts and planispheres. I almost never know the Ra and dec of the thing I am looking at. I tried to use that information early on, but gave up. I may use it on occasion to find something obscure by knowing the offset in declination and RA from something that is easy to find. If you have a goto scope, it uses this information, but you can simply show it something like Capella, Betelgeuse and Aldebaran. It knows what theri coordinates are, and figures out where it is, and goes and finds other obfects using the RA and declination. My mount is not very accurate anyway, and the declination circle got bashed one day, so I straightened it with a pair of pliers. It hasn't affected my viewing. :clouds2:

Hope this helps,

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