When Rosario looked at him, Cathal spotted it immediately because he'd already been watching her. Sure, he'd looked at the space display as well but... well, Rosario was really pretty and really intriguing and those were things one couldn't help but look at.
Being caught out observing her, Cathal gave a little smile - slightly embarrassed - and turned his attention back to the movie instead. He didn't know if he could just imagine her eyes were still on him.