NGC 470 & NGC 474
 Interacting Galaxy Pair
NGC 470:
aka PGC 4777, MCG 0-4-84, Uppsala 858
Nearly face-on spiral
Integrated Visual Magnitude: 12.6
Apparent Diameter: 2.8' x 1.5'
Mean Surface Brightness: 23.1 mag/arc-sec2
NGC 474:
aka Arp 227, PGC 4801, MCG 0-4-85, Uppsala 864
Lenticular
Integrated Visual Magnitude: 12.4
Apparent Diameter: 6.2' x 5'
Mean Surface Brightness: 25.0 mag/arc-sec2
 Minimum requirements to view: six-inch scope from dark site

This pair of interacting spiral galaxies are relatively large and bright, yet unobserved by most amateurs.  Walter Scott Houston observed them in a 4 inch refractor.  He felt that NGC 470 was the brighter of the two.  It's a difficult comparison.  Although close in size and brightness they appear radically different in the telescope.
NGC 474 (bottom-right in the image) has a very bright core, which dominates the view. An elliptical haze surrounds this core, oriented roughly north-south.  A large aperture instrument will reveal a slight glow that extends much farther from the galaxy--much of the way to its neighbor. In my 18-inch on a night of average seeing and transparency I was able to make out a glow about 1/3 of the way to the other galaxy.

I felt that NGC 470 was much more interesting in the eyepiece.  This galaxy appears as a bright oval of much higher surface brightness than its neighbor.  At first glance NGC 470 appears both larger and brighter than NGC 474, even though charts and photos show just the opposite.  This is yet another indication of how different the morphologies of these galaxies are.  The bright core and smooth appearance of NGC 474 hides the intricate, yet much fainter surrounding shells.  On the other hand, NGC 470 looks immediately like a galaxy.

Located nearby is NGC 467, a perfectly round smudge, lying near a bright star.  This galaxy is perhaps brighter than its integrated 13th magnitude would suggest.


The field in a 6-inch at 50x.  North is down and east is to the left.

NGC 474 is a shell galaxy.  The shells are the wide arcs that surround the main part of the galaxy (you can see them faintly in the image at the top of the page).  These shells have been modeled on a computer as the result of gravitational interaction with nearby NGC 470.  As NGC 470 passed near its gravity disrupted the thick disk.  The modeling of interacting galaxies such as these helps us understand how galaxies interact when they pass close to one another.
 

Millennium Star Atlas Vol I Chart 243
Sky Atlas 2000 Chart 10
Uranometria 2000 Vol I&II Chart 217

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