Gray tabby cat with green collar

I lost my gray tabby cat yesterday around 7pm near the Yale campus, around College Street and the Green. He's about 9 pounds, short-haired, with a bright green collar and a tiny silver bell, plus a white patch on his chest and a small notch in his left ear. He's normally friendly and will meow when he hears a familiar voice, and I'm really worried because he's been part of my life for years. If you spot him, text or email—I'm hoping to meet near the Yale Bookstore area by the Green to bring him home.