For an attic install that will be fine. If there is a little extra wire sticking out of a connector, you could cut a bit of the extra off, then take it to a big box home center and compare it to their #10 wire. I own wire strippers that have specific notches for each common wire size, the tool makes a good gauge. If you have a machinist caliper. #10 AWG is 0.1019" in diameter.
http://en.wikipedia.org/wiki/American_wire_gauge
If the satellite system was installed using the smaller #12 or #14 ground wire you're better off than most (though the installation would not conform to NEC 810.21).
If you mount outside, I'd encourage you take the time to ground both the mast and the coax shield using a minimum diameter of #10 AWG copper.