UGC 12591


UGC 12591 is the second most massive known spiral galaxy, after ISOHDFS 27. It is located about 400 million light years away from the Earth in the constellation Pegasus. In addition, it is the spiral galaxy with the highest known rotational speed of about 500 km/s, almost twice that of our galaxy, the Milky Way.
The galaxy has a mass estimated at 4 times that of the Milky Way, making it the second of the most massive spiral galaxies known to date.