ngc 2460 and ic 2209 in Camelopardalis

[wimvb]

ngc 2460 lies at a distance of about 70 million light years in the constellation Camelopardalis. The galaxy has an active nucleus and is believed to be interacting with its smaller neighbour ic 2209 (to the right). The arms of the larger galaxy are thin and extend very far, which makes this galaxy a very difficult target. It took 30 hours of exposure time to separate the galaxy arms and the surrounding dust from the noise.

If the weather allows, I will try to add H-a to the galaxies. Interacting galaxies tend to have massive star formation, which the bright blue colour of ic 2209 also hints at. These galaxies usually have bright H-alpha clouds, where the star formation occurs, and more often than not, it pays off to spend a few hours on targets like this with a H-a filter in front of the camera. This is often overlooked by astrophotographers.

Equipment:

SkyWatcher 190MN on an AZ-EQ6

ZWO ASI294MM camera with Optolong LRGB filters

Exposures:

Luminance: 327 x 3 minutes

RGB: 68 + 47 + 53 x 5 minutes

[lrh]

Amazing work - I always love seeing images of active galaxies! Great point about the star formation. It's also worth mentioning that active galactic nuclei also produce a lot of Halpha emission (both from the nuclei themselves and due to them ionising the central regions of the galaxy), so I'm guessing that the Halpha subs will bring out even more central detail in the main galaxy.

Looks like you captured quite a few background galaxies too!

Luke

[Stargazer33]

That's beautiful Wim! The detail & sharpness you have achieved is wonderful to see. I love the colour in ic 2209.

[WolfieGlos]

Nice image Wim, worth the 30H for this 🙂 Loads of background galaxies too, look forward to the Ha addition.

I take it that you've managed to pull out IFN across the field as well?

[wimvb]

14 hours ago, lrh said:

Amazing work - I always love seeing images of active galaxies! Great point about the star formation. It's also worth mentioning that active galactic nuclei also produce a lot of Halpha emission (both from the nuclei themselves and due to them ionising the central regions of the galaxy), so I'm guessing that the Halpha subs will bring out even more central detail in the main galaxy.

Looks like you captured quite a few background galaxies too!

Luke

 

11 hours ago, Stargazer33 said:

That's beautiful Wim! The detail & sharpness you have achieved is wonderful to see. I love the colour in ic 2209.

 

4 hours ago, WolfieGlos said:

Nice image Wim, worth the 30H for this 🙂 Loads of background galaxies too, look forward to the Ha addition.

I take it that you've managed to pull out IFN across the field as well?

Thanks, all.

@lrh, the problem with extended H-alpha is that it tends to produce pink galaxy cores, if not checked. But once I have enough H-alpha data, I'll figure out how to best incorporate it. My usual method is to use red continuum subtraction, which isolates the knots in galactic arms.

@WolfieGlos, I think that I will need at least 10-15 hours of H-alpha. Fortunately nights are still long "up here". And yes, there is some ifn in this area, though not as strong as around M81/M82. The bright cloud on the left hand side is a combination of ifn and the glow of a nearby star.

[wimvb]

I found a thesis from 2014 which discussed the interaction of ngc 2460 and ic 2209. In it was an image of the pair, so I compared it to my result. It seems that I resolved details down to about 24 Mag/arcsec2. Not too bad for a simple 190MN in a Northern European backyard.

Ludwig, J. A Survey of Dwarfs and Tidal Debris around Nearby Massive Galaxies – Deep Imaging with Medium-Sized Telescopes, 2014

http://www.ub.uni-heidelberg.de/archiv/17232

[windjammer]

>>My usual method is to use red continuum subtraction,

Ah, do you have any further info on that ?  I have been looking for a method of reliably adding in Ha for absolutely ages!

Simon

[wimvb]

@windjammer  check this link

https://pixinsight.com/examples/M31-Ha/index.html#Continuum_Subtraction

[windjammer]

Thanks very much for the link - I will give it a whirl

Simon

[tomato]

Great work!

I have looked at Adam Block's image in the Cambridge Photographic Atlas of Galaxies (660 mins integration, 800mm reflector, SBIG STX-16803 from Mount Lemmon SkyCenter) and you have lots more detail in the spiral arms , all those hours make a difference!👍

[wimvb]

57 minutes ago, tomato said:

Great work!

I have looked at Adam Block's image in the Cambridge Photographic Atlas of Galaxies (660 mins integration, 800mm reflector, SBIG STX-16803 from Mount Lemmon SkyCenter) and you have lots more detail in the spiral arms , all those hours make a difference!👍

Thank you, Steve. All those hours were needed, believe me. But Adam's still wins in some regards. Aperture, focal length, and seeing do still make a difference. I sometimes I wonder if a longer focal length and a finer imaging scale would give more detail. Not on paper, probably. But theory isn't everything.

[tomato]

3 hours ago, wimvb said:

Thank you, Steve. All those hours were needed, believe me. But Adam's still wins in some regards. Aperture, focal length, and seeing do still make a difference. I sometimes I wonder if a longer focal length and a finer imaging scale would give more detail. Not on paper, probably. But theory isn't everything.

That’s a debate I’m still having. I have sort of settled on my Esprit 150/ASI 178 combination for small targets, but I still  get the urge to trade the refractor in for a 14” or 16” RC and mate this to a IMX571 sensor and go galaxy hunting at around 0.5” per pixel, but then common sense prevails, knowing my sky can never do this justice.

[wimvb]

4 hours ago, tomato said:

That’s a debate I’m still having. I have sort of settled on my Esprit 150/ASI 178 combination for small targets, but I still  get the urge to trade the refractor in for a 14” or 16” RC and mate this to a IMX571 sensor and go galaxy hunting at around 0.5” per pixel, but then common sense prevails, knowing my sky can never do this justice.

With my MN190/ ASI294MM combo, I always use bin2 at 0.95"/p, but I could try bin1. It's just that the files become so large (97 MB), and the camera specs are a lot poorer.

[windjammer]

You could always try a barlow as an experiment: keep the bin2 but get to 0.5"/pxl. I went through that exercise on my 150/F5 refractor but reverted to prime focus.  Just not enough photons/skies/optics.  Vlad (shhh!) also made convincing arguments. I might revisit though.....

Simon

[tomato]

Since moving to an ASI678c to capture RGB data, I capture the Lum at 1x1 and then decide to downsample in the processing, judging each data set on its merits. Most of the time the down sampling is the way to go, but not always.

[wimvb]

7 hours ago, windjammer said:

You could always try a barlow as an experiment

I only have a few cheap SkyWatcher 2× barlows in my (also cheap) eyepiece kit. Shooting at bin 1 will be easier.