A 9th-magnitude barred spiral (class SBc) in Reticulum (RA 03 18 16, Dec -66 29 55), NGC 1313 is a "starburst" galaxy, in which unusually large numbers of hot, bright young stars are forming. Most such galaxies have recently suffered collisions or near-collisions with neighboring galaxies, but NGC 1313 appears to be essentially alone. It is possible that as in the case of our nearest neighbor, the Andromeda Galaxy, which appears to have been greatly affected by a collision with a nearby dwarf elliptical, NGC 1313 was involved with a much smaller galaxy which is hidden from view, behind it; but barring such an unlikely explanation, there is no good model currently able to explain its unusually active structure.
     The galaxy is about 50 thousand light-years across, and a little less than 15 million light-years distant.

The second Index Catalog adds (per Delisle Stewart) "3 very faint stars close together, no nebulosity"

(See IC 324 for a discussion of the double listing, and problems with occasional misidentification of the object.) Based on recessional velocity of 1210 km/sec, about 55 million light years away, in reasonable agreement with redshift-independent distance estimates of 58 to 75 million light years, considering that for such close objects, peculiar (non-Hubble expansion) velocities can significantly affect the result. Given a distance estimate of 60 million light years and an apparent size of 0.9 by 0.75 arcmin, about 15 thousand light years across.

NGC 1333 is a diffuse nebular region which is forming young stars (many less than a million years old), which are obscured by and illuminate the nebula in a variety of ways. It is classified as a reflection and/or emission nebula, according to the region involved. At the top of the image below, light scattered by dust near a hot blue star is even bluer than the star itself (as in the case of sunlight, scattered by our atmosphere). Below, equally bright stars are nearly hidden by clouds of gas and dust lying between them and us, while near the bottom, other regions glow with the reddish light of hydrogen atoms excited by ultraviolet radiation from stars completely hidden from view. (Jay Lavine and Ali Huang/Adam Block/NOAO/AURA/NSF, NOAO)

The second Index Catalog adds (per Swift) "To be struck out"

The second Index Catalog adds (per Delisle Stewart) "not round, but much extended 140 degrees"

Arp 39 was intended as an example of a spiral galaxy with faint companions. In this case, PGC 12989 (NGC 1347) is the spiral galaxy in question, and PGC 816443 is the faint companion. The system has a recessional velocity of 1760 km/sec, which corresponds to a distance of about 80 million light years. Given that, the 1.5 by 1.3 arcmin apparent size of the larger galaxy is about 35 thousand light years across, while the 0.55 by 0.4 arcmin size of the companion corresponds to about 13 thousand light years.