NGC 7331, Deerlick, Stephan's Quintet, and IFN

[wimvb]

This is (probably) my final version of this popular galaxy group. This image now has 8 hours of luminance data, and double the amount of colour data, compared to my previous version.

425 minutes (7 hrs) of RGB

240 minutes (4 hrs) of Ha

495 minutes (8 hrs) of Luminance

Total time on target: 19 hours

I think it paid off. The image now clearly shows the main galaxy's extended halo, IFN, three of four dwarf galaxies (ngc 7331A, ngc 7331B, ngc 7331C, with ngc 7331D being outside the fov), and a very faint (Mag 27) suspected tidal stream.

Captured with my SkyWatcher 190MN, and ASI294MM camera, at gain 0, -10 C

Processed with boxing gloves in PixInsight ( 😉 @ollypenrice )

I used the data in creative ways. The RGB and Ha data was processed as is. I used continuum subtraction to clean the Ha-signal. For the stars, I selected those subs that had the lowest FWHM and eccentricity values (39 subs), while for the galaxy and ifn, I used all 165 subs.

Combined the lot in several stages in PI.

The annotated version

 

Edited September 27, 2022 by wimvb
changed title

[gorann]

Outstanding Wim, with both nice details and a lot of IFN coming through!

[knightware2]

Beautiful capture Wim!

I don't know whether you know why this is called 'Deerlick Group'. Many years ago (I guess 20-25), an observing friend named Tom Lorenzin was observing in nearby mountains at an overlook area.  He and a few others observed this galaxy group and named it for the overlook parking area. The overlook is in North Carolina (USA) along the Blue Ridge Parkway - a beautiful roadway with several overlooks that are used for astronomical observing when weather is favorable.

My husband & I visited the area in June and took this photo of Deerlick Overlook.

- Phyllis

[wimvb]

2 minutes ago, knightware2 said:

I don't know whether you know why this is called 'Deerlick Group'. Many years ago (I guess 20-25), an observing friend named Tom Lorenzin was observing in nearby mountains at an overlook area.  He and a few others observed this galaxy group and named it for the overlook parking area. The overlook is in North Carolina (USA) along the Blue Ridge Parkway - a beautiful roadway with several overlooks that are used for astronomical observing when weather is favorable.

My husband & I visited the area in June and took this photo of Deerlick Overlook.

- Phyllis

Thank you for the information, Phyllis. I'd never heard of that.

Now I just have to change the title of my post. 😀

[gorann]

 

Phyllis, thank you for giving us that insight into a mysterious name. I found the story now also mentioned here: https://astro.i-net.hu/content/deer-lick-group-ngc-7331-and-stephans-quintet

Edited September 27, 2022 by gorann

[gorann]

17 minutes ago, knightware2 said:

Beautiful capture Wim!

I don't know whether you know why this is called 'Deerlick Group'. Many years ago (I guess 20-25), an observing friend named Tom Lorenzin was observing in nearby mountains at an overlook area.  He and a few others observed this galaxy group and named it for the overlook parking area. The overlook is in North Carolina (USA) along the Blue Ridge Parkway - a beautiful roadway with several overlooks that are used for astronomical observing when weather is favorable.

My husband & I visited the area in June and took this photo of Deerlick Overlook.

- Phyllis

Se comment above, sorry for the double post 😉

Edited September 27, 2022 by gorann

[tomato]

Great image Wim, I guess you know when you have gone deep enough when the IFN starts to come through.
You have probably guessed I’m not a huge fan of this cosmic phenomenon, but hey, it’s part of what’s up there so I’d never photoshop it out, although I rarely get enough integration to detect it.

My Esprit 150/IMX 571 set up has a very similar FOV to your set up, so this is my next project when I put the RASA8 back in the box.

[Sunshine]

It's a wonderful image!

[DaveS]

Yep, that's a great image Wim. I've been thinking about getting more data, that might just be the kick I need. I *should* be able to get the IFN from my site.

[wimvb]

16 minutes ago, tomato said:

Great image Wim, I guess you know when you have gone deep enough when the IFN starts to come through.
You have probably guessed I’m not a huge fan of this cosmic phenomenon, but hey, it’s part of what’s up there so I’d never photoshop it out, although I rarely get enough integration to detect it.

My Esprit 150/IMX 571 set up has a very similar FOV to your set up, so this is my next project when I put the RASA8 back in the box.

Ifn is ok if it’s a natural part of an image, but in galaxy images ”it should be seen but not heard”. Ie, the image shouldn’t scream: IFN! at the cost of the main target. In this image I’m more pleased with the candidate tidal stream and the dwarf galaxies. The tidal stream is supposedly mag 27, which is by far the faintest I have caught ever. In a superstretched inverted L image it stands out very clearly.

[ollypenrice]

That really is a great rendition, Wim. The IFN is coming through very naturally and contributes to the image in this case.  Outstanding.

Olly

[Rodd]

Very nice.  Love the IFN, something completely impossible for me.  It really makes the image interesting