Last week, the National Reconnaissance Office, which runs our country's top secret spy satellites—Hi, Iran!—launched its newest toy. It was a mystery—just a "payload." But within hours, its orbit was tracked, and within days, amateurs astronomers were watching.

There's a dedicated community of non-pro satellite trackers, grinning each time they lock on to one of the government's shadowy space projects: "I was clouded out on Wednesday 4 April, but yesterday evening (5 April) was clear and it was finally my turn," boasts one sat blogger.

Not only was he able to capture this clear video of the satellite nobody's supposed to see gliding across the sky, he was able to deduct just what kind of satellite it is:

Like its earlier sistership FIA Radar 1, FIA Radar 2 is in an unusual retrograde orbit (proving that it is a radar satellite).

Radar satellites are capable of capturing extremely detailed terrain imagery of places of the world that don't like us very much. And now astronomers across the world will be able to follow it wherever it goes:

Over the comings days/weeks the new satellite will probably be actively manoeuvering, so it will be a nice object to keep track off!

The consummate 21st century hobby. [SatTrackCam via FAS]