Incredibly Obvious Bomb: In the Empire, this is the essential difference between a nuclear weapon – which is a specifically military purchase, and using which under most circumstances will have you up on capital Use of Instruments of Regrettable Necessity Without Appropriate Authority charges, and a nuclear device, which you can buy at a good hardware store and is used routinely for digging canals and reservoirs, moving asteroids, dispersing unwanted mountains, and other types of civil engineering.
Namely, that apart from being bright, high-visibility orange, the nuclear device has a ubiquitously networked and geolocative computerized arming system that will refuse to arm itself if you’re inside someone’s city limits or other off-limits property (or part of the affected radius is); that will give the appropriate countdown before detonating to let even pretty leisurely people clear the blast area, and broadcast said countdown (and where it is, what it is, and what its range is likely to be) over the local public caution/warning channel. If anyone’s still inside the blast area, per their geolocation information, when the countdown hits the low numbers, it’ll quietly shut itself down. And it’ll accept a detonation veto command from absolutely anyone within that area, no questions asked. (And, yes, comes with copious anti-tamper devices to prevent anyone from turning it into a nuclear weapon unless they could have built their own nuclear weapon just as easily, if not more so.)
A nuclear weapon, on the other hand, will specifically avoid doing any of that.