ASTRO: Another Saturn Galaxy

First attempt to send this got cut short when power when off. Trying again.
Rick
__________________________


A few weeks ago Tom Davis posted an image of LBN 406, a huge reflection
nebula in Draco Aof all places, in several forums using his 12" F 3.5
astrograph. http://www.tvdavisastropics.com/astr...s-1_000081.htm
He noticed a galaxy PGC 58928 that looked like Saturn. It is small in
his image and suggested I image it. I did another Saturn like galaxy
last fall. NGC 6470.
http://www.spacebanter.com/attachmen...6&d=1223320472
It too is in Draco just a bit further north. It has a fainter outer
ring besides the Saturn ring. It's ring is small so it's hard to see
much detail at my seeing level. NGC 6470 is rather near by at about 62
million light years. PGC 58928 is much more distant at 400 million
light years. It doesn't have an outer ring. You'd expect at over 6
times the distance it would be really small but it actually appears
larger in our skies so is more than 7 times the size of NGC 6470. A
giant of a barred spiral galaxy in fact. Though in Tom's wide angle
shot it appears about the same size as my shot of NGC 6470 and except
for the outer ring seems a "ringer" for NGC 6470. Things change at my
higher resolution however. There we see it is really a barred spiral
with the typical elongated core and bar structure, The two arms at
first appear to come from the same end of the galaxy but that's an
illusion as they pass so close to each other due to perspective at the
left side of the core they appear to unite then split again. I'm sure
this is an illusion and higher resolution would show this not to be the
case. The ring is really two nearly, but not quite, overlapping pair of
arms rather than a real ring. There are a few star clusters in the arms
though all but one are close to the core. There may be more below my
resolution level. The one note in NED does refer to the arms as
"smooth" without mentioning these clusters. That I don't understand.
Note that Tom's image is rotated clockwise 90 degrees from mine with
east at the top rather than north. While there are a lot of other
galaxies in the image (many look like stars at Tom's image scale) none
have redshift data that I could find. There's also a galaxy cluster at
the left edge (east) of my image. The core galaxy of which appears as a
rather bright orange star in Tom's image. It is ZwCl 1647.0+5943 and
has 88 members but again, no red shift data. Due to this one being at
the edge of a nebula the background is rather uneven and brighter toward
the upper right. At first I thought my flats were in error but after
looking at Tom's much deeper image it appears this is just due to
picking up some of his nebula in my far shorter exposure.

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

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".

Rick,

great detail in this small galaxy, although it would probably look even more
like Saturn if you had less resolution :-)

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
First attempt to send this got cut short when power when off. Trying
again.
Rick
__________________________


A few weeks ago Tom Davis posted an image of LBN 406, a huge reflection
nebula in Draco Aof all places, in several forums using his 12" F 3.5
astrograph. http://www.tvdavisastropics.com/astr...s-1_000081.htm
He noticed a galaxy PGC 58928 that looked like Saturn. It is small in
his image and suggested I image it. I did another Saturn like galaxy
last fall. NGC 6470.
http://www.spacebanter.com/attachmen...6&d=1223320472
It too is in Draco just a bit further north. It has a fainter outer
ring besides the Saturn ring. It's ring is small so it's hard to see
much detail at my seeing level. NGC 6470 is rather near by at about 62
million light years. PGC 58928 is much more distant at 400 million
light years. It doesn't have an outer ring. You'd expect at over 6
times the distance it would be really small but it actually appears
larger in our skies so is more than 7 times the size of NGC 6470. A
giant of a barred spiral galaxy in fact. Though in Tom's wide angle
shot it appears about the same size as my shot of NGC 6470 and except
for the outer ring seems a "ringer" for NGC 6470. Things change at my
higher resolution however. There we see it is really a barred spiral
with the typical elongated core and bar structure, The two arms at
first appear to come from the same end of the galaxy but that's an
illusion as they pass so close to each other due to perspective at the
left side of the core they appear to unite then split again. I'm sure
this is an illusion and higher resolution would show this not to be the
case. The ring is really two nearly, but not quite, overlapping pair of
arms rather than a real ring. There are a few star clusters in the arms
though all but one are close to the core. There may be more below my
resolution level. The one note in NED does refer to the arms as
"smooth" without mentioning these clusters. That I don't understand.
Note that Tom's image is rotated clockwise 90 degrees from mine with
east at the top rather than north. While there are a lot of other
galaxies in the image (many look like stars at Tom's image scale) none
have redshift data that I could find. There's also a galaxy cluster at
the left edge (east) of my image. The core galaxy of which appears as a
rather bright orange star in Tom's image. It is ZwCl 1647.0+5943 and
has 88 members but again, no red shift data. Due to this one being at
the edge of a nebula the background is rather uneven and brighter toward
the upper right. At first I thought my flats were in error but after
looking at Tom's much deeper image it appears this is just due to
picking up some of his nebula in my far shorter exposure.

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

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".