I just submitted a bug report on this: ticket ID #1,252,551.
The background lights in AT seem to flicker during any movement and in a not-uniform way. There's shifts between normal background and what appears to be a blue-silvery overlay, but it's happening very oddly and is extremely jarring when the ship is moving.
This does not happen in any other sector- only Alpha Trianguli.
I'm running windows xp, DX9, and an nVidia 9800 GTX OC+ graphics card.
EDIT: Also, while you're at it, you may *really* want to fix the sector sign from Alpha Tri to Sirius, as despite multiple bug reports and posting in a thread where you asked to report on any appearances of it, it still says KLINGON instead of Sirius Sector Block like it should.
I noticed this exact same problem this morning as I was passing through all the Cardassian sectors on that "See the Universe" challenge event. It almost looks like z-fighting or an alpha-sorting glitch in the milky textures that make up the backdrop. I almost thought it was my video card failing, but then I noticed it was only happening in that one sector.