How to read this orbital graph?

[Windows]

Hello
I'm not a professional cosmologist but I wanted to know what the orbital length is equal to in Km units in this graph: http://ej.iop.org/images/1538-4357/707/2/L114/Full/apjl334146f3_lr.jpg

Thank you so much.

 

[wotanub]

That graph shows right ascension and declination. These "sky coordinates" allow you to trace out the path of the object in the sky as viewed through a telescope. I don't think this is enough information to determine the how far it is away from the body it is orbiting.