NGC1365 and Fornax Group 43 hours

[Paul Haese]

I have been collecting data on this target for what seems like an eternity. Although there is lots of data collected I feel the Luminance could do with some more data. I had to do a little smoothing to the Luminance channel to control the errant noise in the darker areas.

Lum 19 x 30 minutes = 9.5 hours
Ha 34 x 30 minutes = 17 hours
Red 16 x 20 minutes = 5.333 hours
Green 14 x 20 minutes = 4.666 hours
Blue 16 x 20 minutes. = 5.333 hours

Of note is the reddish background to the right of the image. This showed up in the red, Ha and luminance channels. Since there is no light source in the area I am thinking it is meant to be there. I do wonder though if it was some high cloud passing through. However, given that each channel was captured on different nights I am inclined to think this is some intervening gas in between. Although I could be completely wrong. I just don't know.

I am not sure if I like the way the image looks, I spent a lot of hours processing it and trying to achieve a nice balance.

What I really like about the image is the amount of galaxies captured within the field. Nearly every where you look you can see lots of galaxies. Given the size of the aperture I am pleased at what has been captured.

Click here (http://paulhaese.net/FornaxClusterNGC1365.html)for image.

New image added with gradient removed.

[alpal]

Wow - what a great pic with so many galaxies.

[niharika]

Paul, I love it. That TSA can deliver. You must be under a very dark sky to achieve 30min Lum.

[Paul Haese]

Thanks Paul.



Yes readings here range from around 21.5 to as high as 22.06 on an SQM-L. It is pretty dark here on moonless nights. When it is clouded out you definitely need a torch.

[strongmanmike]

It is a great field that one Paul, the contrast between the spiral and ellipticals makes for an almost unique scene. Congrats on the mega data too...43hrs huh? Must make you happy ;) :thumbsup:

All minor processing comments but because you like the techo-perfecto feedback :thumbsup: yeah, I can see the smoothing (shame after so much exposure - just can't win :doh:) and Hmmm? the red looks like a slight gradient maybe? Of course the big elliptical is indeed huuuge and there is galactic cirrus and galaxy cluster glow (http://www.pbase.com/strongmanmike2002/image/147311115/original) there too :question: I do see a blue gradient on the left side too though :shrug: no biggy to me.

Overall, especially for an itty bitty 4", it is a great result, nice work :thumbsup:

BTW that's a lot of Ha data there...did it assist?..or was it just coz you can :lol:

Mike

[RickS]

Very nice wide look with lots of background galaxies, Paul! You went pretty deep on 1365 as well. Would be well worth revisiting with the 12" from your dark skies.

Cheers,
Rick.

[multiweb]

Great field and colours. Very smooth. :thumbsup: Although it's heavily clipped. Have you checked your histogram? I reckon there might be a lot more background data to be had given the total integration time.

[Paul Haese]

Yeah the lots of hours makes for easier processing. You could be right about gradients but I think this is most likely in the lum channel. I was thinking it might be gradient too, but did see some slight brightening on the right and not much on the left in the various channels. I might need to remove some subs from the lum and collect some to replace the those removed. See if that makes a difference.

I think half the problem with the lum needing smoothing is that the aperture just cannot collect the light needed quickly. A larger aperture would certainly make a huge difference.

Not sure if the Ha was worth the effort, but I collected it during the full moon cycle as well as the HH Ha data, so it was clear and thought I would try. I might be a different story with a larger aperture.





Yes definitely on my target list for the RC12. Too late to get to it this season but I will next. I took an image of this with the RC8 quite a few years ago now and it is crap really and the image needs to be replaced with a much more thorough image.



Yeah thought that might be the case. The image out of photoshop is fine, when I made it ready for web I adjusted the gamma and this black point clipped it. I have now replaced the image and that not clipped. Your thoughts?

[SpaceNoob]

Wow. Love the glows coming off the brighter targets. Really shows how the larger data runs can really push out the image. Well done with your latest project. This galaxy is a great target. There's so many out there it's good seeing all these galaxy shots lately. Looking forward to more!

Chris.

[jase]

Not sure Paul. Mega data doesn't equate to a mega result, at least this time. I'm sure the data is fantastic but it could have been handled differently. As Mike highlights there is definitely a gradient. Not sure what techniques you use to 'proof' your work but if you take the jpeg you've uploaded into photoshop - Image | Adjustments | Equalize.

With Equalize, photoshop finds the brightest and darkest values in the image and remaps them so that the brightest value represents white and the darkest value represents black. Photoshop then attempts to equalize the brightness. This will emphasise the gradient making it easier to visualise the direction, colour and helps to check the result after gradient removal has been applied. This will also be contributing to the data being clipped in the shadows. Which you'll see in the lower left of frame. Gradient removal will clean that up (you'll see it histogram too). I didn't realise this was a Ha rich area - is it?

[madbadgalaxyman]

Gday Paul,

As mike said, a lot of amateur exposures just begin to pickup faint light in between the galaxies of a galaxy cluster.
This light is probably not coming from anything unusual (such as glowing embers, or burning copies of the Astrophysical Journal, or weird atomic particles)....most studies find that the intracluster light in Galaxy Clusters comes from stars in the extremely-extended halos of the ellipticals or it comes from stars that orbit in the potential of the cluster rather than in the potential of any individual galaxy.
(isolated stars are probably existing that have orbited to the outer parts of galaxy clusters.....these must be the loneliest places in the universe!)

My feeling is that you are picking up the intracluster (inter-galaxy) light in this galaxy cluster, though it is hard to prove it, as the biggest elliptical galaxy NGC 1399 is so vastly extended.

I am very interested in your Ha data.
The whole point is that there is not supposed to be much Ha (or extremely little Ha) emission in the central parts of the Fornax Cluster near the big ellipticals;
however, given that Ha emitting streamers were discovered in between some of the Virgo Cluster galaxies, it would be worth checking the Ha frame to see if there is anything unusual there.

Thanks for your big imaging effort on the Fornax cluster, as it is very much "our" nearby major cluster in the southern hemisphere; it is still much less understood than the Virgo Cluster, which the "northies" have extensively characterized.

best regards,
Robert

[madbadgalaxyman]

G'day Jase

Indeed, the galaxies of the Fornax Cluster are particularly "red and dead", especially near the elliptical-galaxy-rich core of the cluster;
most of these galaxies have not had significant star formation for billions of years. Therefore, there should be little or no Ha emission in this cluster, as this requires the existence of newly-formed stars that are 10 million years old and younger.

In this respect, Fornax Cluster, which is much more centrally concentrated and symmetric than the Virgo Cluster, can be thought of as a "highly evolved" galaxy cluster.

But the whole point is to look for the unexpected from time to time, so I think the idea of Ha data on this region is an interesting "shot in the dark".
(not likely to hit anything, but a worthwhile experiment)

Another possibility that could produce Ha emission in a galaxy cluster that has only old stars is the presence of AGN (seyfert ; quasar) activity, which can produce so much far-ultraviolet that it can light up gas clouds that are a long way from a galaxy.

I suspect that at least some of the light seen near NGC 1399 in Paul's image is not an artefact, and that this light will be from the galaxy itself, as it has a most extensive halo.

cheers,
Robert

P.S.
It is an odd fact that there is actually an enrmous mass of gas, even in Elliptical & S0 dominated clusters like the Fornax Cluster; only problem is that it is at millions of degrees, so it ain't ever going to form new stars!

[jase]

Robert,
Are you aware of a Ha survey that has been done in the area? It is difficult to find references. MWE centered (http://galaxymap.org/mwe/mwe.php?centreLon=337.840576171875&centreLat=-34.797363281249986&zoom=5&tile_set=integrated_ha&show_markers=1) on Achernar which is 28 degrees away from NGC1365 is not a good reference. Unfortunately MWE is just that, a Milky Way Explorer so not helpful to the cause.

I guess we have a few things to check before we (read 'I') get all excited about the discovery of "Paul's Intergalactic Nebula".


check the accuracy of the flats by measuring ADU in corners and that post application they have not introduced the gradient - possible
verify darks and bias are being subtracted correctly - amp glow
evaluate blue and green filtered data for presence of light - linear stretch - ADU checks again - on raw FITS data
check for optical train/camera light leaks - unlikely
Check if presence of light exists when target shot at different locations in sky. If dark sky site not an issue - unlikely

[alistairsam]

Really cool image Paul.
I did a quick alignment of yours and Mike's to see the different results with aperture, exposure length (Mike's was 90mins lum??), processing styles, camera etc. (hope that's ok)
most fuzzies are present in both and also cool to see the SN dissappear from Paul's. not sure how far apart these are.


Cheers
Alistair

[Paul Haese]

Hmmm, bit blunt there Jase. Not sure what your agenda is here. You rave about a certain imager's images and those look like noise central, have elongated stars everywhere and not well colour balanced, and you don't bang him with a sledge hammer.

Yes there looks to be a gradient and I recognised that. I am currently applying a gradient map and thanks for the tip; I think.:question:

I don't think Robert is trying to say I discovered anything at all. Nor am I even thinking along those lines. However, just for your information I will respond to your queries.

1. The flats are accurate.
2. Darks and biases are being subtracted accurately. Or would you like to check my work yourself?
3. Blue green filter data is fine.
4. No light leaks. Everything is screw fitted from the OTA to the camera.
5. The site is a dark site. 5 street lights in the whole town and the nearest is 600m away. If you look around the rest of my images you might find this is not the norm in my images.

I don't really care if this is important to you or not, but the way you have addressed this seems like you think less of me. Your words seem to imply I don't know what I am doing and that is disrespectful. Tell me what is wrong with the image but also tell me what you think is right.

[Paul Haese]

I have done a gradient map over the image. I think this is better. I am working in a bright room here so not ideal for me seeing what is really going on. So forgive if things are not right. I will review the image tonight in a better viewing environment.

Larger image has been replaced but I provide a smaller image here for comparison.

[allan gould]

Paul
Hate to be picky with your image as it really looks great - except for the gradient which is still there.
I could still see it in your re-posted image and so I took the liberty of a fiddle with it.
The first image is your latest and the next is my presumptuous one. Just hope you see a difference.
Regards, Allan

[jase]

No agenda Paul. Feedback was constructive along with items to check. I'm pleased to hear you have confirmed these are all ok. If you took these questions as though I don't think you know what you are doing, you've got it all wrong and taken it way too personally. Apologies. Happy to discuss- skype cpjase. I'm actually hoping you are onto something with the light background appearance toward the top right given no amateur image has gone so deep of this area that I can recall. The image shows that you've put in a lot of time and energy producing this image, and the 43hrs of data alone talks dedication. The image has a lot going for it with solid colour balance and saturation to name a couple. The background is however very distracting in my opinion, whether accurate or not. Perhaps there are signs of galactic cirrus being masked by the uneven background. More than happy to have a go at working your mega data set over if you are offering. Try some inverse masks to stretch the background hard to see what's lurking there while masking the stars and foreground objects.

Looking forward to seeing the repro.

[Paul Haese]

Done and accepted, thank you. :)

[gregbradley]

Awesome work Paul. An amazing effort - 43 hours on a widefield. That's very exciting. Also its proof that excellent optics in a small package can still deliver the goods. I love small refractors myself.

I am joining this thread late on and I can see you've already implemented a few changes so the latest image to my eyes looks sensational.

One thing about gradients. When I am at my dark site which is also totally dark and good seeing I sometimes still get a minor gradient. This used to puzzle me until I started doing some DSLR nightscapes and I saw how often there is sky glow. Sky Glow is usually green but as the latest image from Antu in the nightscapes beautifully shows it can sometimes be shades of red/magenta. So perhaps you caught a bit of that and also as you are fairly south perhaps even some Aurora one night. I am not sure high cloud would create a reddish area like that. If there had been high cloud the stars would have been fuzzy which is the first thing you would notice.

Of interest to me is the elliptical galaxy in the bottom right. Is it just me or is there a hint of a tidal stream there going down to the bottom right corner? I'd love to see a nice inverted image to see that more clearly.

You are obviously doing the most you can to do the best of imaging and the hard work is showing in results here.

Greg.

[Paul Haese]

Yeah the gradient is a puzzle given I shoot mostly in the east and there is no light source for 700 or so kilometres.

As requested here is a link to an inverted image. Hope that suits. I don't think there is a stream though.

For the size this refractor does all right but the seeing at Clayton makes the refractor really perform. Guide parameters in the last month of so have been around 0.1 at worst and 0.01 at best.

Click here (http://paulhaese.net/FornaxClusterNGC1365inverted.html)f or image (its full res too)

[alpal]

Hi Paul,
I saw the gradient but was not worried about it.
When you try to get rid of it it's too easy to remove faint galaxies.

I looked for other details.
You have a lot of details of the giant elliptical NGC 1399.
see link:

http://cseligman.com/text/atlas/ngc13a.htm#1399

Your choice of framing is amazing.
It's so great to get all that in one frame.

[Bassnut]

Excellent work Paul, stuff em all, I like it. Allans repro is pretty good though, so dont stuff him.

[Lee]

I think we are getting too damn picky around here.... it's a cracker of an image.... well done.

[Derek Klepp]

Thanks Paul my favourite Galaxy.

[gregbradley]

Thanks for that. It looks like its more an extended halo.
Great site. Seeing like that is rare anywhere in the world.

Greg.

[strongmanmike]

To whom are you referring here Paul, Rob Gendler? Martin Pugh, Don Goldman..? :)

[madbadgalaxyman]

Hey guys, cool it!!

Your debates about imaging are remarkably technical, and they impress a humble galaxy morphologist like me.

Your discussion level reminds me of group of professional astronomers having a disagreement.

Certainly, all of you have taken amateur imaging to levels which were inconceivable even a decade ago.

I am in awe of the achievement of the amateur imagers in IIS!!

When people get really knowledgable, essentially professional, about a topic, they tend to nitpick, and arrogance is not far away. After all, if you are really good at something, a certain amount of arrogance is natural.

My advice, regarding this much too heated discussion, is that really it is all about having fun....

And there is the important issue, which has nothing to do with emotion, of how to bring out the extremely extremely faint details in images.
cheers,
Robert

[Shiraz]

lovely smooth image Paul - looks great and a very interesting group.

[Paul Haese]

Thanks guys, I really appreciate you taking the time to comment.

Mike, non of the above but you know now who I mean.

Robert, yes I think you are correct. In then end though forums and discussions tend to increase the level of perfection and the standard of imaging. I am certain that the internet has raised the imaging level by mega levels to what it might have been had it not existed. The dissemination of information has had a crucial impact on imaging in general. Not to mention other areas in astronomy. So I for one don't mind constructive criticism but I do like to hear what people like about my images too.:)

The next image will be along in about 30 hours time. It is closer to home though.;)

[prokyon]

Wow, sooo deep! Great work, I love galaxy groups, this one is a stunner.

[IanP]

Awesome Paul, an amazing effort of so many hours ...
:thumbsup:

[E_ri_k]

Nice one Paul. So many galaxies there. Great detail, even in that tiny galaxy in the top of your image.

[Rigel003]

Hi Paul. I've been swamped with work of late and only nowjust caught up with this. Great image! All those background galaxies make me think of the Hubble Deep Field (the 4" equivalent). My favourite is the tiny spiral near the blue star, top centre.

[Paul Haese]

Thanks Guys for the comments.



Thanks Graeme, Yeah I suppose it is the 4" equivalent. That galaxy is pretty cool looking. Though I am pretty interested in the slightly edge on near the top center too.