Amazed to read on the WikiPedia entry for Huygens probe
http://en.wikipedia.org/wiki/Huygens_probe that it is expected that the
location of Huygens probe on Titan's surface will be located to within 1
km . This corresponds to a precision of more than 1 part in a billion -
equivalent to splitting an E coli bacterium at a distance of 1km.

Now that's what I call an accurate measurement!

The rest of the WikiPedia article is the best I've read about Huygens
(or any other mission come to that).

Superb!