Condottiere
Emperor Mongoose
How do you estimate where it is going to be if you never knew where it was to begin with?
Edit - and I believe I said, by the rules. Your response had no rules attached to it.
1. Unless I'm mistaken, gunners would aim for centre mass.
2. The gunner is told that it's necessary to take out a spacecraft that happens to being manufactured in the construction deck.
3. Schematics are called up, and let's assume the construction deck is centralized, but towards the ass end of the it's installed spacecraft.
4. The gunner adjusts the aim hundred metres to the right.
5. If the dice gods are with him, the meson delivers it's load exactly hundred metres to the right of centre mass.
6. The gunner has done his job, and unless the explosion is enough to blow out the walls of the construction deck, whether the target is actually damaged or destroyed, would be unknown.
7. Or, the gunner could keep on blowing his load in the middle of the targetted spacecraft.