Historical Note: The galaxy and its spiral nature were discovered by David Malin in 1986 (whence its designation "Malin 1"). It is now classified as a giant (extremely) low surface brightness galaxy (= GLSBG), and it is the first and so far largest such galaxy discovered. A 2014 paper by Galaz et al based on observations with the 6.5 meter wide Magellan/Clay telescope (in Chile) showed that it is even larger than previously thought and discussed details not previously observable.
Physical Information: Based on a recessional velocity relative to the Cosmic Background Radiation of 25115 km/sec (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that PGC 42102 is about 1170 million light-years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 1060 to 1065 million light-years away at the time the light by which we see it was emitted, about 1105 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 1.75 by 1.75 arcmin (from the images below), the galaxy is about 540 thousand light-years across, or about 5 times the size of our Milky Way galaxy.
Classification Note: The type shown in the description line is based on the overall structure of the galaxy. The bright central region, which looks more like a barred lenticular galaxy, is usually classified as type SB0/a.