fk triplet with only ONE identified moving targets.

[brettgladman]

BG notes that

fk_13BL+3-1_s10.measure3.reals.astrom

has only ONE moving target identified after validate. This
seems impossible. Unsure on count, but I think that 3 or
4 were proposed, and I rejected the others. The probability
of having only 1 implanted target found is low enough that
this triplet should be looked at.