The place is on the first level where the Neimodian is in a control room by the generator you need to destroy. There are two boxes; one contains a full health pack. The box next to it contains a thermal detonator. But you can't just push it off the edge to get it. You must cause the elevator to lower, then as it comes up shove the crate onto it. The crate will shatter. Get onto the elevator, and a thermal detonator will be floating in midair above the lowered elevator. I found it by using "perf"---I noticed it's wire frame image inside the floor when I shoved both crates on the security droids.
I have not seen this secret in any walkthroughs. Has anyone else found it?

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At last we will reveal ourselves to the Jedi.
At last we will have revenge.

Cool! There is always something new with this game!