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ASTRO: NGC 7594 and friends



 
 
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  #1  
Old August 9th 13, 08:10 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: NGC 7594 and friends

NGC 7594/IC 1478 is an enormous spiral galaxy in Pegasus, just below the
Great Square. It is about 470 million light-years distant. To be so
large in my image at nearly a half billion light-years it has to be big,
about 205,000 miles in diameter as seen in my image. Unfortunately the
night was very poor and it likely is even larger. IC 5305 at 460
million light-years is a likely companion. The distance difference is
likely quite small, just that their relative motion makes the redshift
distance larger than it really is. NED shows it part of a three galaxy
group WBL 706. Obviously IC 5305 is one of those two other galaxies but
I can't determine which is the third.

Below these two is the flat galaxy 2MFGC 17488 at 530,000 million
light-years. Well to the west is another galaxy, KUG 2315+100 that is
also about 530 million light-years distant. They are likely related but
if part of the WBL 706 group that's 4 not three. Plus IC 5307 near
2MFGC 17488 is at 540,000 million light-years. But no three galaxy
group at that distance is shown in NED.

2MFGC 17488 appears to be a companion of IC 5306 but it is 200 million
light-years further away so they are just a chance alignment rather than
a true pair though many catalogs list them as pairs.

NED shows only these galaxies with redshift data. Since there were only
a few other galaxies even listed in NED I went ahead and noted them on
the annotated image even though they had no redshift. All were from the
2MASS catalog of IR galaxies. That is likely why the blue galaxies in
the image, marked by question marks, while bright, aren't listed. They
just don't have the IR emissions to make the 2MASS catalog.

The quality of the night was very poor. Much is lost I'm sure. The
evidence for this is the lone asteroid shown in the image (135118) 2001
QT117. It shows at two places in the image rather than a constant trail
as these normally do. This is because clouds were so bad only 2 of the
4 frames used showed the asteroid at all. 4 others taken between these
were were even worse than the two I used that didn't show it. This
explains the broken trail. The color frames were very poor as well with
many of them thrown out. Two blue ones were fair and were used. All
green and red were very poor but I picked the two best for each. Thus
the color is somewhat questionable. I did have to make a large
reduction in the blue channel to get decent color. It still may be too
blue.

One known casualty of the clouds was the plume on 2MASS
J23183301+1014088, east of IC 5307. It has a plume to the east that is
only faintly seen in my image. On a reasonable night it would have come
through quite well.

14" LX200R @ f/10, L=4x10' RGB=2x10' (due to clouds less than half that
many photons captured), STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

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ID:	4690  
  #2  
Old August 9th 13, 08:00 PM posted to alt.binaries.pictures.astro
Stefan Lilge
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Posts: 2,269
Default ASTRO: NGC 7594 and friends

Rick,

a very nice enormous but little galaxy. Makes me look forward to fall,
although I just found a most interesting target for further summer imaging
:-)

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

NGC 7594/IC 1478 is an enormous spiral galaxy in Pegasus, just below the
Great Square. It is about 470 million light-years distant. To be so
large in my image at nearly a half billion light-years it has to be big,
about 205,000 miles in diameter as seen in my image. Unfortunately the
night was very poor and it likely is even larger. IC 5305 at 460
million light-years is a likely companion. The distance difference is
likely quite small, just that their relative motion makes the redshift
distance larger than it really is. NED shows it part of a three galaxy
group WBL 706. Obviously IC 5305 is one of those two other galaxies but
I can't determine which is the third.

Below these two is the flat galaxy 2MFGC 17488 at 530,000 million
light-years. Well to the west is another galaxy, KUG 2315+100 that is
also about 530 million light-years distant. They are likely related but
if part of the WBL 706 group that's 4 not three. Plus IC 5307 near
2MFGC 17488 is at 540,000 million light-years. But no three galaxy
group at that distance is shown in NED.

2MFGC 17488 appears to be a companion of IC 5306 but it is 200 million
light-years further away so they are just a chance alignment rather than
a true pair though many catalogs list them as pairs.

NED shows only these galaxies with redshift data. Since there were only
a few other galaxies even listed in NED I went ahead and noted them on
the annotated image even though they had no redshift. All were from the
2MASS catalog of IR galaxies. That is likely why the blue galaxies in
the image, marked by question marks, while bright, aren't listed. They
just don't have the IR emissions to make the 2MASS catalog.

The quality of the night was very poor. Much is lost I'm sure. The
evidence for this is the lone asteroid shown in the image (135118) 2001
QT117. It shows at two places in the image rather than a constant trail
as these normally do. This is because clouds were so bad only 2 of the
4 frames used showed the asteroid at all. 4 others taken between these
were were even worse than the two I used that didn't show it. This
explains the broken trail. The color frames were very poor as well with
many of them thrown out. Two blue ones were fair and were used. All
green and red were very poor but I picked the two best for each. Thus
the color is somewhat questionable. I did have to make a large
reduction in the blue channel to get decent color. It still may be too
blue.

One known casualty of the clouds was the plume on 2MASS
J23183301+1014088, east of IC 5307. It has a plume to the east that is
only faintly seen in my image. On a reasonable night it would have come
through quite well.

14" LX200R @ f/10, L=4x10' RGB=2x10' (due to clouds less than half that
many photons captured), STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

  #3  
Old August 9th 13, 08:34 PM posted to alt.binaries.pictures.astro
Skywise
external usenet poster
 
Posts: 318
Default ASTRO: NGC 7594 and friends

Rick Johnson wrote in news:520495f0$0$49311$862e30e2
@ngroups.net:

about 205,000 miles in diameter as seen in my image.


WOW!!!! That's huge!!!

Somebody was typing in their sleep?

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?
 




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