The Earth is the Center of the Galaxy...
When was the last time you stood in the center of the galaxy?  I'm going to guess NEVER!!!!  We are on earth so don't you think a coordinate system with the earth as the origin would be easier for astrologist to use.  This is called the Equatorial Navigation System.  Instead of the origin being the center of the Milky Way, the origin is the earth itself.
   
Imagine you are using the Chandra software to investigate a celestial object.  You just found out how far away the object is, what the object is made of, and how fast it is moving.  However, you want to see it in the night sky.  How can Chandra help you find it?
       
 

1)  Open any image of interest...say the short exposure of the Centaurus Cluster

2)  On the tool bar go to "WCS".  Make sure there are two red dots next to "WCS" and "galactic".

3)  Move the cursor over the object and observe the reading on the WCS display.  Note the latitude and longitude.

4)  Now go to the Galactic Map and locate the Centaurus Cluster. What a coincidence, the Centaurus Cluster is in the middle of the Centaurus constellation.

  
       
     
Now you know where the Centaurus Cluster is in relationship to the center of the galaxy, but where is it with respect to earth?
       
   
First we need to download some FREE SOFTWARE that will allow you to view the sky with respect to the earth.  Once you have the software installed continue with step one below.
  
       
 

1)  Change the coordinate system to "Equatorial" as shown below.

2)  Place the cursor and find the coordinates of the Centaurus Cluster in the display.

3)  Now open the CyberSky software and move the cursor until the equatorial coordinates match up.  You may not be able to find the coordinates.  Why do you think this is?  Why can't we see the sun at night? 

If you are having trouble finding the coordinates, fast foward the chart hour by hour until your coordinates are displayed.  Then you can see where they are in the sky.

 

Now you can use Chandra to locate celestial objects in the sky relative to earth, and relative to the center of the galaxy.

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