TheSkySearchers

NGC 7640 is a barred galaxy close to edge-on - SB(s)c. It lies in a relatively dense foreground star field along with some faint cirrus. NGC 7640 is about 26 million light years distant by Tully-Fisher estimate and about 26.8 million light years (by redshift estimate).

There are a number of background galaxies - one identified by PGC ID others by 2MASS - none have distance estimates. There are a number of other visible background galaxies, but they are only identified as IR sources. The visible Quasars are are from 4.279 to 9.165 billion years (Lookback or light travel time).

Image and details can be accessed at the link below (or by clicking on the image crop below). The annotated image has a link below but it can also be accessed from the main image webpage as well - or seen on astrobin. The full FOV image can be accessed from the image webpage and has an image scale of about 0.59 arcsec/pixel.

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    NGC 7640 Region

Annotated Image:
NGC 7640 Region Annotated

Images also available on astrobin - https://www.astrobin.com/l3tw9y/

Scope: Celestron 9.25 Edge HD 235 mm at f/7
Camera: ASI294MM (Baader LRGB Filters)
Location: DAA Observatory, Shelter Valley, CA

Wonderful image! Great work, Jim!!

Good work and like it.
Thanks.
Rog.

Very nice capture Jim!

Beautiful image Jim.
I really enjoy reading your descriptions and love the annotations!
The quasars are fascinating and fantastic captures!

nice take , thx .

Great image Jim.

Like the detail you teased out in the "bar". Nice shot.

Nice one Jim. Your always interesting explanations caused me this time to learn about the difference between the redshift approach and the Tully-Fisher approach to determining galactic distances. Thanks for always sharing your insights with us.

Steve

Thanks for the comments folks!
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STEVE333 wrote: ↑Sun Mar 19, 2023 10:52 pm Nice one Jim. Your always interesting explanations caused me this time to learn about the difference between the redshift approach and the Tully-Fisher approach to determining galactic distances. Thanks for always sharing your insights with us.

Steve

Thanks Steve.
Galactic distances are kind of interesting and certainly inexact and indirect. I generally refer to the quantitative values as "estimates" and should be considered approximate. They are quite a bit different than stellar distances based on parallax - which can be as accurate as the underlying measurement. As objects are more remote, the "distance concept" takes on less relevance anyway. Tully-Fisher is notable historically but gets get less useful and inaccurate past about 100mpc (326 million light years). After that it's redshift - but measuring redshift on light that has been traveling for, say 11 billion years, seems to imply that your "direct" redshift measurement has a lot of latency built in.

We now see lots of new and interesting ways to measure the universe - Astrophysics is evolving so rapidly. I could barely hold some of the concepts (much less the math), but now I am pretty much lost. I think I'll just have some fun making pretty pictures.

Another lovely image and, as others have said, interesting and educational information also. Keep at it Jim!

Hi Jim. A very nice NGC 7640 image especially on the astrobin site using your Celestron 9.25 Edge HD telescope. Excellent contrast, well framed, and spiral arms details visible in the this semi edge-on galaxy. Thanks for sharing this capture with us Jim and the best of wishes for many clear skies.