The amateurs are able to do this by looking at a range of things including tyre tracks in snow at the entrance and exit of launch sites, as well as by looking at whether cranes are in place or not. They're also looking at indicators such as when a launch system trailer turns up to deliver fuel.
A slide showing expansion of a prison in North Korea. Photo: Ben Grubb
Nuclear reactor testing sites have also been closely monitored by the amateurs, Mr Jorm added.
Website 38 North, a site devoted to analysis of North Korea, in particular had been analysing North Korea's use of a nuclear reactor and found in November 2012 that a trench was being dug to run coolant piping out to the reactor.
By January this year, Mr Jorm said the reactor had been seen as "ready to rock".
A slide shows tyre tracks at a satellite launch site, which indicated when it was bout to be launched. Photo: Ben Grubb
"This is no longer [government's] exclusive domain," Mr Jorm said of watching North Korea. "With the data that is now publicly or commercially available independent individuals can also do this [satellite] analysis."
Mr Jorm said satellites typically updated imagery for certain spots once every two to four days due to their orbit. In spite of this, online sleuths still managed to draw inferences from them.
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