They're moving to attack position. Shields up.
8 seconds sound clip from the Star Wars: Episode V - The Empire Strikes Back movie soundboard.
You can hear this line at 01:07:33 in the Blu-ray version of the movie.
Quote context
[...]
- Turn her around. I'm going to put all power in the front shield.
- You're going to attack them?
- Sir, the odds of surviving a direct assault on an imperial...
- Shut up!
- They're moving to attack position. Shields up.
- Track them. They may come around for another pass.
- Captain Needa, the ship no longer appears on our scopes.
- They can't have disappeared. No ship that small has a cloaking device.
- Well, there's no trace of them, sir.
- Captain, Lord Vader demands an update on the pursuit.
[...]