Answer:
3
Explanation:
The process is called triangulation and involves at least 3 stations.
The principle is that from each station, you get a distance location from that station of the event. Then from each station you make a circle with the distance measured at that station.
All three circles done form the monitoring station will meet at a point somewhere between those three stations, and you'll get your location.
That's the triangulation process. You do need 3 points for a precise reference, if you have only 2, you are usually left with 2 possibilities.
