Physical Information: One of a pair of interacting galaxies referenced in the HST image below as UGC 2369. It is obviously interacting with its companion, so their average recessional velocity should be used for estimating their Hubble distance. For PGC 10938 that is 9355 km/sec, and for PGC 10939 it is 9760 km/sec, making their average recessional velocity about 9555 to 9560 km/sec. Based on that (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that the pair is about 445 million light years away, in reasonable agreement with redshift-independent distance estimates of about 375 to 455 million light years. 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 425 to 430 million light years away at the time the light by which we see it was emitted, about 435 to 440 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 0.45 by 0.35 arcmin (from the images below), PGC 10938 is about 55 thousand light years across.

Physical Information: One of a pair of interacting galaxies referenced in the HST image below as UGC 2369. It is obviously interacting with its companion, so their average recessional velocity should be used for estimating their Hubble distance. For PGC 10938 that is 9355 km/sec, and for PGC 10939 it is 9760 km/sec, making their average recessional velocity about 9555 to 9560 km/sec. Based on that (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that the pair is about 445 million light years away, in reasonable agreement with redshift-independent distance estimates of about 375 to 455 million light years. 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 pair was about 425 to 430 million light years away at the time the light by which we see it was emitted, about 435 to 440 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 0.75 by 0.4 arcmin (from the images below, but not counting the dust lanes extending into PGC 10938), PGC 10939 is about 90 to 95 thousand light years across.