Ngc 3621

[rogerg (Roger)]

Hi all,

A recent effort, cut short by clouds before the full moon kicked in.

12” SCT @ 2180mm 0.84”/pixel; ST8-XME; L=450min R=310min G=290min B=180min

http://rogergroom.com/spiral-galaxy-ngc-3621/

For my standards of LRGB imaging the colour isn't bad I think, but am undecided if I've pushed the fainter regions a little too far and so am showing a bit too much noise.

Regards,
Roger.

[madbadgalaxyman (Robert)]

Hi there Rog,

Thanks for an interesting image of this challenging object.

Gee those arms look like they are of very low surface brightness.
I didn't even think of this fact when I was trying to characterize this galaxy in this thread: (within the third post)
http://www.iceinspace.com.au/forum/s...d.php?t=133011

I should have had a look at the surface brightness, which would have modified my "theoretical" conclusions about the size of this galaxy's OB star population, which arose as a result of navigating the numerical data in the galaxy catalogs!
The moral of this story is "take your mind off the data and actually have a look!"

The disk/spiral component of this galaxy is very very interesting;
- it is not planar
- it is extremely extremely extended, far beyond the borders of your jpg
- this may be a case of an 'unevolved' galaxy, where the outer arms and disk are still in the process of formation.

cheers,
Robert

These faint and very very extended disks are pretty hot in the current literature, as the GALEX ultraviolet images bring them up to a bright level of visibility.
Some people call them "XUV" disks, which is short for "extended ultraviolet disks"

e.g. Mr Sidonio has made a nice image of the extended disk of NGC 1512:
http://www.flickr.com/photos/strongman/15614965059/

[rogerg (Roger)]

Thanks Robert.

Mr Sidonio does a great job doesn't he , I just re-visited his attempt at this one which shows much more detail in the outer arms.

[Shiraz (Ray)]

very nice image Roger. Those outer regions really are faint - don't think you have a problem with noise.