NGC 3509
Arp 335
UGC 6134
PGC 33446

Leo

RA 11 04 23.6
DEC 04 49 43

Type: Galaxy
Class: SA(s)bc pec

Size: 2.3' x 1.1'

Magnitude: 13.0

Discovered by Herschel in 1786 and later cataloged by Dr. Halton Arp as Arp 335 in his Peculiar Catalog, NGC 3509 is quite a galaxy. On the surface, images of NGC3509 give it an obvious tadpole appearance of which you could conclude that you're looking at one galaxy. But the interesting fact is that its actually two. Astronomers using the HST released a paper in 2003 stating that NGC 3509 is an elliptical experiencing a slow on-going interaction with a smaller galaxy. Best I could determine is that if you were to look at the inner edge of the main part of the galaxy, the blueish knot is actually the core of the interacting partner. Having observed this object quite a few times over the years. I always just assumed that it was just one galaxy.

As I did research for this weeks OOTW, I noticed in Dr. Arps book that two knots apparent in NGC3509 are labeled as KPG265a and KPG265b. (The knot I mention above is KPG265a)These designations are from the Karachentsev Isolated Pairs of Galaxies Catalog created in 1972 by Russian astronomer I.D. Karachentsev. So did astronomers know for certain that NGC3509 was a multiple system back in 1972? I guess they must have, correct?

Visually NGC3509 is moderately large but dim. Though I have found just a couple observing reports online with scopes in the 15-16" range, having a rather large surface area makes its listed magnitude of 13 quite deceiving. This OOTW can definitely be tough to eek out detail. In my 25" from my western Illinois skies, I tend to make out an uneven oval shaped glow. Below are a couple of my notes

March 2012 - 25" f/5
"sort of faint elongated glow. single arm visible with averted. At 350x and 393x I can see the arm easier and it extending back and towards the core. The core is non stellar with a knot near the edge"

I did manage to observe this galaxy once with the 48" in which the tadpole shape was quite obvious as was the knot mentioned above:
February 2009 488x
"wow does this look like a tadpole! The single arm is apparent and wraps beautifully back towards the galaxy's core. The core appears stellar and bright with a small bright know right at the inside edge"

Its funny how I looked at this knot thinking it was most likely a star forming region of 3509. Little did I know that years later I would find out that it was in fact the core of another galaxy! NGC3509 is well placed this time of year in Leo. Next time you're out, check and see just how much detail you can get out of this galactic collision!

And remember,

"Give it a go and let us know!
Good luck and great viewing!"


NGC3509-SDSS.jpg big_arp335.jpg