[amsat-bb] ISS/STS-126 Position?

Hi All: Do the keps for the shuttle become in accurate at some point during a docking mission? My tracking programs show STS-126 on the other side of the world from the ISS now, even though they are docked. They were showing them approaching each other yesterday up to a point, then they began to diverge. I notice they are very far apart this AM with updated keps. The ISS position is the correct one, and it's not that big of a deal, just curious as to why this happened?

Scott/WB2UZR

PS Had a nice view of the launch the other night from the backyard!