Galaxies galore below the paws of the Great Bear

[wimvb]

Or plain and simple: Abell 1185 in Ursa Major

I spent two nights gathering data for this one. Two nights ago gave me 10.5 hours of RGB, and I completed the data collection yesterday night with 6 hours of Luminance.

Abell 1185 is a group of galaxies, some 400 - 450 million light years distant in the constellation Ursa Major. One of the more interesting members in this field of view is ngc 3561, which actually consists of several galaxies, ngc 3561, ngc 3561 N, and ngc 3561 Irregular. Equally interesting is that there are more galaxies in this images than there are stars. Most of the background "gnats" are distant galaxies and quasars, up to 6 billion light years distant.

As always, I used my trusted 190MN and ASI294MM with Optolong LRGB filters

Processed in PixInsight. I drizzled the Luminance master, so even this crop is quite a large size.

 

And by the way; that isn't Saturn in the lower right corner. It's ngc 3536, 500 million light years distant. It has a very nice double ring structure.

Edited March 11 by wimvb
increased the background

[ONIKKINEN]

Great image.

What an interesting tidal tail to the left of the center in the image. One can only assume those 2 galaxies recently (cosmic timescales speaking) had a collision and one was torn apart.

[WolfieGlos]

Wow, what a fascinating image and looks great zoomed in too - so many galaxies!

That tail almost looks like a guitar....the guitar galaxy maybe?

[wimvb]

9 minutes ago, ONIKKINEN said:

One can only assume those 2 galaxies recently (cosmic timescales speaking) had a collision and one was torn apart.

Three galaxies, actually. There is an irregular galaxy in the plume at the end of the tidal structure.

10 minutes ago, ONIKKINEN said:

Great image.

 

Thank you.

[wimvb]

Just now, WolfieGlos said:

Wow, what a fascinating image and looks great zoomed in too - so many galaxies!

That tail almost looks like a guitar....the guitar galaxy maybe?

Thank you. That's why I drizzled the luminance data. The "guitar galaxy" are ngc 3561, ngc 3561 N and ngc 3561 Irregular (from bottom to top).

[bomberbaz]

very impressive image, I envy the skies you must have to image such tight data, I grow tired of my garden results and yearn for such as you display here.

Loving the intereacting galaxies too, these cosmic dances impress me on a number of levels, well done!

[wimvb]

Thank you, Steve, for your kind words.

53 minutes ago, bomberbaz said:

I envy the skies you must have to image such tight data

I had the good fortune to be able to move away from the Stockholm suburbs, to the countryside. It's not very dark, but at least there are no street lights, and only one neighbour whose house is behind ours.

[gorann]

Just amazing and very zoomable! Do you think drizzling made any difference?

[wimvb]

14 minutes ago, gorann said:

Just amazing and very zoomable! Do you think drizzling made any difference?

Thanks, Göran. I think drizzle in combination with BXT made a difference. Guiding during the night that I collected the luminance for this image was about 0.8", so not that great. With a pixelscale of 0.955" and the atmosphere as it is, I wasn't undersampled. Drizzle shouldn't have done much, but since BXT seems to like oversampled data, I think the combination improved the final image. Btw, the colour data wasn't drizzled, I just upsampled it to match the luminance pixel scale.

[gorann]

5 minutes ago, wimvb said:

Thanks, Göran. I think drizzle in combination with BXT made a difference. Guiding during the night that I collected the luminance for this image was about 0.8", so not that great. With a pixelscale of 0.955" and the atmosphere as it is, I wasn't undersampled. Drizzle shouldn't have done much, but since BXT seems to like oversampled data, I think the combination improved the final image. Btw, the colour data wasn't drizzled, I just upsampled it to match the luminance pixel scale.

I only tried drizzling a few times and remember that I got really big files that slowed processing down. At least for my RASA data with a pixel scale near 2" I do not think it would help it I got the theory right.

[wimvb]

1 hour ago, gorann said:

I only tried drizzling a few times and remember that I got really big files that slowed processing down. At least for my RASA data with a pixel scale near 2" I do not think it would help it I got the theory right.

you've got colour cameras, so all images have three channels. That makes them three times as large as my mono images. As I wrote, I stacked the RGB data without drizzle, and only L at drizzle x2. I also have a smaller sensor than you, my fits files are 23.4 MB out of the camera. The camera resolution is half that: 11.7 Mpixels.

Normally I don't drizzle either. With this image I just experimented with it, and I think it paid off. For nebula images, where the level of detail isn't that critical, drizzle isn't necessary in my opinion.

[ONIKKINEN]

I'd say drizzling was worth it, it really doesn't look drizzled or oversampled to my eyes. I've also found that BXT likes higher resolution data, and have been processing data at native 0.76'', usually resampled to 1'' resolution in the end rather than the bin2 1.52'' that i previously swore on.

There is theory and there is practice, i dont think theory has quite caught up on modern tools, especially BXT.

[Roy Foreman]

My god its full of galaxies, to sort of quote a famous movie line. Excellent result, nice work.

[wimvb]

4 hours ago, Roy Foreman said:

My god its full of galaxies, to sort of quote a famous movie line. Excellent result, nice work.

Thanks, Roy. I guess you could call it the 'Holland Hill deep field'. (Since I'm dutch and live on a hill/ridge near the swedish village Lindholmen, I named my observatory Holland Hill Observatory.)

What movie was that, btw?

[Roy Foreman]

It was from 2001 a space odicy when astronout Dave Bowman uttered the words  'My god its full of stars'.  A very old film now, but something of a cult I think.

Yes, Holland Hill Deep Field seems very fitting !

[wimvb]

Full size annotated version with QSO's, galaxies, galaxy clusters, brightest galaxies in a cluster, LEDA, NGC, plus a few unidentified objects

[ollypenrice]

Lovely image.

Olly

[Paul M]

It is a magnificent image, and my favorite deep sky subject; mind boggling galaxy fields!

I might take the liberty of downloading and solving it myself, so I can look further into it.

Nothing but cloud and drizzle here soneeds must!

[tomato]

Fabulous image, glad to see it entered into the Deep Sky Survey competition. It’s inspired me to change cameras and have a go at something similar, assuming I can get a clear night and and the dome operational.

[wimvb]

2 hours ago, tomato said:

Fabulous image, glad to see it entered into the Deep Sky Survey competition. It’s inspired me to change cameras and have a go at something similar, assuming I can get a clear night and and the dome operational.

Thanks! I am, as sailors say, dead in the water. Yesterday I started on a new project, but after the meridian flip, my mount started misbehaving. At first I thought a cable pulled the mount and the clutch had come lose. Today the problem persisted. I connected the hand control and noticed a strange sound from the RA axis. It seems that the RA stepper motor has a mechanical failure. I just ordered a replacement from Pierro-Astro in France. Hopefully, I will be able to fix the mount before the season ends. If not, this is going to be my final image until after the summer.