(See IC 146 for a discussion of the double listing.) Based on recessional velocity of 10595 km/sec, about 475 million light years away. Given that and apparent size of 1.0 by 0.5 arcmin, about 140 thousand light years across.
Above, a 1.2 arcmin wide closeup of NGC 648 Below, a 12 arcmin wide region centered on the galaxy