Based on a recessional velocity of 15945 km/sec, a straightforward calculation indicates that IC 4588 is about 750 million light years away. However, for such distant objects, we must take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that IC 4588 was about 700 million light years away when the light by which we see it was emitted, 715 million years ago (the difference between the two numbers is due to the expansion of the intervening space during the light-travel time). Given that and its 0.5 by 0.45 arcmin apparent size, the galaxy is about 100 thousand light years across. (Note: A Wikisky search for IC 4588 shows NGC 6051. A search using the PGC listing or its coordinates shows the correct object.)