Physical Information: Based on a recessional velocity of 10830 km/sec (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that PGC 33198 is about 505 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 480 to 485 million light years away at the time the light by which we see it was emitted, about 490 to 495 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 1.3 by 0.9 arcmin (from the images below), the galaxy is about 180 to 185 thousand light years across. PGC 33198 is classified as an AGN (active galaxy nucleus) galaxy, due to the bright light emitted by material falling into a supermassive black hole at its center; it is also one of the strongest sources of laser-like microwaves, or a "megamaser", which is the reason its image was featured in the Jan 1, 2018 HST press release linked from its image's credit line.

PGC Designation: The ring galaxy is listed in HyperLEDA as "PGC 4074669", but a search of the database for that designation returns no result, hence its being in quotes. To do a search in either LEDA or NED use the designation SDSSJ110352.74+405056.6.
Physical Information: Arp 148 represents a collision between two galaxies which created the ring galaxy and peculiar lenticular galaxy apparently emerging from it. The linear spiral galaxy (PGC 33423), approaching from the right, passed almost directly through the center of the other galaxy, removing most of its nucleus and causing a wave of star-forming which, passing outward through that galaxy, gave it its ringlike appearance. The peculiar appearance of the pair was first noted by Nicholas U. Mayall in March 1940, whence its name. The pair is used by the Arp Atlas as an example of a galaxy with an associated ring.
 Based on a recessional velocity of 10350 km/sec (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that Arp 148 is about 480 to 485 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 pair was about 460 to 465 million light years away at the time the light by which we see it was emitted, just over 470 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 0.4 by 0.25 arcmin (all apparent sizes from the images below), the ring galaxy is about 50 to 55 thousand light years across, and its companion's apparent size of about 0.35 by 0.15 arcmin corresponds to about 45 to 50 thousand light years. The approximately 0.55 by 0.35 arcmin apparent size of the pair corresponds to about 75 thousand light years.

Physical Information: Based on a recessional velocity of 8675 km/sec (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that PGC 33487 is about 405 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 390 million light years away at the time the light by which we see it was emitted, about 395 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 0.6 arcmin (from the images below), the galaxy is about 40 to 45 thousand light years across. PGC 33487 is used by the Arp Atlas as an example of a three-armed spiral galaxy.