That question catches Rosario for a moment. See, she's written down every single detail of what she can remember from that night, about the stars that spoke to her and the stars that didn't. She's printed out star charts from that exact location, for that exact date and as exact a time as she can figure. She spent an hour at Merlin's just scouring tomes on symbolism and astrology for all the potential meanings of a bird, a river, swimming, drowning. She's spent a lot of time fixating on what she saw, but it's only just now, at Lyra's asking, that she considers what she didn't see. And it's not comforting.
"...no." She frowns. "I mean, I didn't see him, or Boötes. It was just Corvus, it was a crow in a big river and it was flapping its wings around and it couldn't get out. I don't know what it means. But I'm not sitting on it this time around, okay?" she adds, and she clasps Lyra's hand a little tighter, making it a promise. "That's why I'm telling you now. I'm gonna work on it with Merlin. He says if I can focus in on the vision, maybe I can get some more out of it."