A new sort of cloaking device

[Shizune]

It could be many things, ranging from basic military jamming devices all the way up to heat detection inhibitors.

http://discoverygc.com/forums/showthread.php?tid=131023

In this case, its not actually invisible to scanners or anything of the sort. Rather, the cruiser is just inhibiting the other ships senor's array to the point it would detect nothing.

As for the jamming tech..to be fair, many many places around Sirius should have such, from what I know, most ships, even snubs, have some form of jamming..though perhaps an advanced array of some kind maybe? I dun know.