sensor validation, I'd say "most likely within 40nm" is something a little less conservative than saying "most likely the Sun will not have gone out when it should rise in the morning." I'd use most likely for that annulus I described rather than for the entire region. The rest of the 40nm region is less likely but not utterly unlikely - erm, with the exception of the area +/- 30 degrees of the reverse course. To the rear the region would be punched in. That's why I always sorta head scratched over their nice perfect circles.