A source bearing is the compass heading, relative to a sensing node's fixed installation position, of the sector that recorded the strongest response during a rotational sweep.
A responder told that gas is elevated has to search a bay. A responder told which sixty-degree sector it is strongest in has a quadrant. That difference is most of the value during the window in which a hazard is still cheap to arrest.
Each stop in a sweep produces a full channel sample. The peak stop's heading is the bearing. Range is then estimated by inverse-magnitude scaling and combined with the node's registered position to give a source coordinate.
A node at a known position on the plan reports a bearing with a confidence figure. The azimuth is well constrained by the sweep; the radial distance is much less so, which is why the confidence travels with the coordinate everywhere downstream.
The bearing, its confidence and the full angular profile are stored on the investigation, and independently as a footprint so recurring hotspots accumulate into site knowledge.
