Kim Kardashian, Heidi Klum and others attend amfAR's New York Gala

Kim and Kourtney Kardashian hit the red carpet at amfAR's 21st annual New York Gala on Wednesday. The sisters were on hand to help celebrate honorees, celebrity photographers Mert Alas and Marcus Piggott, who received the "Award of Courage in recognition of their longstanding commitment to the fight against AIDS."