I did a search, but I'm not finding anything related to my question. I'm also using a first printing of TacOps, so there may be some issues.
Thunder-Augmented mines deliver a minefield size equal to half the missile flight's strength rounded up (p.373). That means the target hex and the six surrounding hexes targeted by a Thunder-Augmented LRM 5 each receive a 3-point minefield.
The minefield density table on p208 lists target numbers for detonating a minefield. Problem is, it begins at 5. How does a 3-point minefield figure in terms of this table? Does it requires the same to-hit as a 5-point minefield, or does it scale like the rest of the table?
Also, the text on the same page about reducing the minefield's density doesn't account for 3-point minefields. It states that every time a minefield explodes, it can be reduced by one 5-point increment, but never falls below 5 points. Is a 3-point minefield just treated as impossible to reduce, since it is already below the minimum?