Physical Information: PGC 17532 is a multi-armed result of merging galaxies. Based on a recessional velocity relative to the Cosmic Background Radiation of 10645 km/sec (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that PGC 17532 is about 495 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 475 million light-years away at the time the light by which we see it was emitted, about 485 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). The only other distance estimate available is about 520 million light-years, from an HST press release that gives no reason to prefer that value over the one obtained from the Hubble Flow calculation; but since any distance estimate is uncertain, a compromise of about 500 million light-years seems appropriate. Given that and its apparent size of about 1.15 by 0.95 arcmin for the entire structure and about 0.35 by 0.2 arcmin for the central galaxy (from the images below), the central galaxy is about 50 thousand light-years across, while its outer arms span about 165 to 170 thousand light-years.

Note About Classification: The type is taken from the Spitzer Survey of Stellar Structure in Galaxies.

Note About Classification: The type is taken from the Spitzer Survey of Stellar Structure in Galaxies.