Actually 4618 is Arp 23 in the same class. I imaged it some time back.
Rick


Stefan Lilge wrote:
Another very intersting object. Looks a bit like NGC 4618 and 4625.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...

I'm returning to Arp galaxies with Arp 24, NGC 3445 in Ursa Major.
Looking at my image you might think it belongs under the class of spiral
with bright companions on arms but that would be wrong. It's classed
under one armed spirals. The galaxy that appears to be on the end of
that arm, PGC 32784, isn't mentioned by Arp. Red shift shows NGC 3445
to be 103 light years away while the apparent companion, PGC 32784, has
a red shift distance of 88 million light years. Most sources however
consider these an interacting pair even with the different red shift
distances. The difference can be due to gravitational interaction and
not a real relative distance indicator. There are two other galaxies in
the image that are quite likely associated with Arp 24. They are NGC
2440 to the upper right at about 100 million light years and NGC 3458 to
the upper left at a red shift distance of 91 million light years.

The spiral structure of Arp 24 isn't all that well defined with the one
arm being very broad and ill defined. It is full of star clusters and
likely emission nebula if my resolution were higher.

NGC 3440 has a blue knot that carries the Sloan Digital Sky Survey ID as
a separate galaxy SDSS J105352.10+570728.7. I really think it just a
star cloud in NGC 3440 however as it is also cataloged as SBS 1050+573.
The SBS catalog is a listing of emission line nebula though a few
emission line galaxies have made the list as well. I can't find enough
to be certain which it is. NGC 3440 points up to the left at two
galaxies. The brighter is SDSS J105411.24+571016.2 and shows a red
shift distance of 2.5 billion light years. That has to be one enormous
galaxy to be so big and bright at that distance! The dimmer one is SDSS
J105409.41+571017.5 but I can't find any redshift data on it. Further
left and a bit down is SDSS J105432.29+570932.5 at 900 million light
years.

The other galaxy near Arp 24, just to its left is SDSS
J105445.50+565958.8 at 646 million light years.

On the left edge near the bottom are two galaxies. The one on the right
is 2MFCG 08528 at 1.17 billion light years. The other is PGC 32881 at
636 million light years. At the bottom, a bit right of center near a
blue star, is MCG +10-16-020 at 633 million light years. While quite
small it appears it too might be a one armed spiral.

Arp's photo of this galaxy with the 200" Hale telescope, rotated with
east up rather than north up as my image, is at:
http://nedwww.ipac.caltech.edu/level...ures/arp24.gif

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME
Image scale 1" per pixel

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".





--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".