When using an omni weapon in an nebula, there are some strange inconsistencies regarding the targeting system. In particular, displaying a target, acquiring a target, seeing a target, and firing on a target all follow different rules.

Displaying the currently targeted ship is always done, regardless of whether the player can detect it. While keeping the target registered is fine, targets that cannot be detected by ship sensors should probably have their orientation and distance hidden.

Acquiring a target and firing on a ship seem to be doable at the same range, which is significantly shorter than the range at which the player can see a ship that is hidden in a nebula. The code for partially obscuring ships hidden in nebulae should be adjusted so that, when the targeting system will refuse to acquire a target and omnidirectional weapons will refuse to aim at it, a ship is not at all visible to the player. It's somewhat confusing to be able to see a ship clearly but not have your controls recognize that it's there.