Galaxies and galaxy clusters in Ursa Major

[wimvb]

Right under the back paw of the Great Bear, is this collection of galaxies and galaxy clusters.

The largest object in this image is galaxy ngc 3180 or ngc 3184, it seems to have two entries in the new general catalogue. It is situated at a distance of 40 Mly according to Wikipedia, but only about 26 Mly according to its redshift (0.00197). The galaxy is of type SAc, a spiral galaxy with active star forming regions, which I tried to enhance by collecting Ha as well as RGB. The angular size of this galaxy is only about 7 arc minutes, giving it a diameter of about 55 000 light years, half the size of the Milky Way.

Below ngc 3180 is ngc 3179, a lenticular galaxy at a distance of about 325 Mly, according to its redshift of 0.02385. Althought it is catagorised as a lens shaped galaxy, it seems to have some structure in its disc (unfortunately not visible in this image).

If you draw a line through the long axis of ngc 3179 upwards to the left, and another straight down from ngc 3180, you will find, at the intersection, a low surface brightness galaxy, [HKK2009] dJ1018+4109, which is at about the same distance as ngc 3180. In the image, the galaxy barely clears the noise floor. This galaxy is a dwarf galaxy in the local super cluster. Its diameter is about 4 400 light years.

Towards the lower left corner is galaxy cluster ACO 971, at a distance of 1.2 billion light years. This cluster contains some 37 identified member galaxies.

If you go from ngc 3180 to the left, near the edge of the image is emission line galaxy SDSS J102101.03+411946.6, at a distance of 2.55 billion light years. In contrast to "normal" galaxies, this galaxy does not emit a continuous light spectra. In stead, its spectrum is an emmision line spectrum.

Going from ngc 3179 towards the right edge, is low surface brightness galaxy MCG+07-21-035 (23 Mly distant and 2 300 Ly diameter).

Finally, below MCG+07-21-035 is another galaxy cluster, [SPD2011] 2168, which is situated at a distance of approximately 3.6 billion light years.

Details:

• L: 80 x 150 s
• RGB: 25 x 150 s (per channel)
• Ha: 45 x 300 s

Telescope & camera: MN190 + ASI294MM with Optolong 31 mm LRGB filters and Baader 7 nm Ha filter

I first integrated all 160 L subs that I had collected during March and early April, but upon closer inspection, I decided to only use half of these. The other 80 subs had FWHM values that were too high. Ha is very weak in this galaxy, and the Ha master still has a lot of noise in it. If the weather permits, I would like to collect another 40 or so Ha subs. Unfortunately the nights are getting awfully short now, only about 3 hours of astro-darkness for the coming week. Although it is possible to collect Ha even outside astro-darkness, the increased noise will mean that I have to collect even more subs. Astro-seasom will be over soon.

Edited April 10, 2021 by wimvb

[symmetal]

Great image and info. I thought it was M101 at first glance but NGC3180 is also known as the Little Pinwheel Galaxy. 😀  

Alan

[wimvb]

6 hours ago, symmetal said:

Great image and info. I thought it was M101 at first glance but NGC3180 is also known as the Little Pinwheel Galaxy. 😀  

Alan

Thanks Alan. You're correct, its popular name is the little pinwheel. But this galaxy is a lot dimmer than its big brother, and only 1/3 its real (not angular) size.

[gorann]

Beautiful collection Wim! Another success for the Mak-Newt! People should hurry to buy an MN190 before they stop making it - there was some rumor about that about a year ago but it is apparently still for sale.

[kirkster501]

Very nicely done.

[wimvb]

53 minutes ago, gorann said:

Beautiful collection Wim! Another success for the Mak-Newt! People should hurry to buy an MN190 before they stop making it - there was some rumor about that about a year ago but it is apparently still for sale.

Thanks, Göran. Maybe time for yours to come out of the closet (literally). If I had a place to put it, I would very much like to have one more. But unfortunately, my mount won't carry two.

[wimvb]

46 minutes ago, kirkster501 said:

Very nicely done.

Thank you, Stephen.

[Thommy]

Nice one!

Actually, NGC 3184 is the galaxy, while NGC 3180 and NGC 3181 are star clusters in the galaxy.

I like your images for several reasons - one is that I own a mn190 as well and consider to purchase the ASI294MM PRO camera, and so I have a good chance to see what to expect! Keep posting!

/Thommy 

[wimvb]

25 minutes ago, Thommy said:

Nice one!

Actually, NGC 3184 is the galaxy, while NGC 3180 and NGC 3181 are star clusters in the galaxy.

Thanks, good to know.

26 minutes ago, Thommy said:

Keep posting!

I stll have a few in the pipeline, but astroseason is coming to an end up here, with a horrible blueshift. 😋