Sylvia is part of the Cybele family of asteroids (including Camilla, Hermione & Liriope) & Flora is part of the Flora family of asteroids (aka Ariadne; including Alice, Nietzsche, Bulgaria, California & Kafka).
asteroid families were first noticed by Japanese astronomer Kiyotsugu Hirayama who noticed that groups of asteroids shared similar orbits. asteroid families probably result from the catastrophic breakup of a larger asteroid. families named after the first asteroid discovered in the family, which is usually the largest & can be considered the "prototype" of the family. Flora asteroids have a semi-major axis between 2.1 AU and 2.3 AU with an inclination of less than 11°; Cybele asteroids have a mean orbital radius between 3.27 AU and 3.7 AU, an eccentricity less than 0.3, and an inclination less than 25°. Cybele asteroids cluster around Jupiter's 4:7 resonance.
British astronomers Norman Robert Pogson discovered asteroids Isis, Ariadne, Hestia, Asia, Sappho, Sylvia, Camilla & Vera; and John Russell Hind discovered Iris, Flora, Victoria, Irene, Melpomene, Fortuna, Kalliope, Thalia, Euterpe & Urania. Pogson formalized the system of stellar magnitudes (see Pogson's Ratio); Hind discovered the first nova of modern times — Nova Ophiuchi (V841 Ophiuchi image) — stargate #24 RAS ALHAGUE is also in Ophiuchus.