WOW such an exceptional image very inspiring for me personally just setting up my observatory with 10" Newt to show what can be achieved and to strive for perfection.
Gets my vote for APOD.
Yes, it can be difficult to pick out any Intracluster light from the Integrated Flux Nebula. I've aligned a (linearly stretched) image from the WISE survey (12um W3 band) which may help.
In the survey image you can see many faint bands and patches, including a slightly brighter patch to the right of NGC 3258, which may confuse the identification of a intracluster bridge to the NGC 3268 group.
Based on the published radial velocities in the Principal Galaxies Catalogue and measuring the angular distances between NGC 3258 and 3268, these two galaxies are probably 1-2 million light years apart, so there could well be a stellar stream between them. There's quite a large difference (about 1000km/s) between the radial velocities of NGC 3258/3268 and 3269 which would normally mean that NGC 3269 is about 50Mly further away. However, it's more likely though that the large difference in radial velocity is just relative motion within the cluster, so there could also be a faint intracluster bridge between these galaxies too.
Last edited by SamD; 06-08-2015 at 05:53 PM.
Reason: Wrong re interpreation of radial velocity within cluster
Your dedication has resulted in a spectacular image. Thanks very much for posting the luminance stacking results. Most interesting! Like Jase I am very curious about your methodology for dealing with such a large data set.
Fantastic write up and sublime work Rolf, grattis.
Will need to revisit this on my large monitor!
Ps also surprised you managed to nab 55 nights in 6 months!
Regards
Russ
Thanks very much Russ, yes the weather was pretty good here early in the year. As you can see from the bar chart I had a very good run in first half of Jan and another in Feb. Then as winter arrived there were fewer clear nights.
Quote:
Originally Posted by Atmos
Can I just quickly say... I am in love with that telescope
What you have done is spectacular Rolf, I mean truly amazing. Just about to start zipping through the full res now but WOW
Thanks Colin, I think the telescope performs very well too. The Royce mirror is a joy.
Quote:
Originally Posted by Nicola
An amazing job for an outstanding image, well done indeed!
Glad you liked it Nicola!
Quote:
Originally Posted by rmuhlack
Inspiring, visionary work yet again Rolf. Surely this is the bleeding edge frontier of amateur astrophotography, internationally.
Thanks a lot Richard, I like to do these projects and try to reveal something new every now and then.
Quote:
Originally Posted by Somnium
simply fantastic. amazing detail and it is extremely interesting seeing the difference in the Luminance integration time and its impact on the data. did you limit your imaging sessions to good seeing conditions or did you take cloud free nights when you got them ? this is the type of astrophotography that is simply inspiring. congratulations on your efforts, it was well worth the wait.
Thank you Aidan, I'm glad you liked the integration collage too. I included that to illustrate that it really does make a difference, also after 100+ hours.
Quote:
Originally Posted by strongmanmike
Very cool Rolf.
This is one of those images that is not really full of spectacular looking colorful features like the Sagittarius Trio, Vela SNR or Orion regions and a casual passing look might even find it a bit boring...so it is not until you look carefully and realise what it is that you are actually seeing here that the enormity and achievement is realised. The write up is very useful to facilitate this too, very well done
I have considered imaging this cluster a few times in the past but considered it a bit lacking in interesting looking galaxies...but then I wasn't considering spending 6 months imaging it either so thank you for doing the hard yards (understatement) and producing a deep and intriguing vista
Mike
Thanks very much Mike, I'm glad that I could relieve you of the chore of imaging this cluster . I did have the same thoughts initially; that this cluster might not be particularly interesting, but that perception quickly changed as I got more data and began to research the limited literature on it.
Since publishing the image I have also had confirmation from scientists that the Intracluster Light seen here is indeed real and not previously described, so it was nice to get a confirmation of my own analysis and interpretation
Quote:
Originally Posted by andyc
Comments and critique? I'm not sure I'm fit to critique your shoelaces... extraordinary image! And thanks for sharing the results of your massive project, and the interesting bits of research around features in the image - those dust clouds in front of the galaxy are very unusual.
Thank you Andy, I'm glad you found it interesting as I do like to provide some background and analysis along with my images.
Quote:
Originally Posted by cometcatcher
So, this is the big project you have been working on. To say it's truly spectacular is an understatement!
Thanks Kevin!
Quote:
Originally Posted by alpal
Hi Rolf,
I admire your work.
This has got to be an APOD.
The universe looks so large & interesting with deep pictures.
I would like to see the same entire picture in LRGB
but with say only 1 night equivalent of time - say 3 to 5 hours
just to get a comparison.
(I see you posted a single galaxy with many different total exposure luminance frames.)
I really think that what you're doing is the future of amateur astronomy if we want to do something of great scientific value.
cheers
Allan
Thank you very much Allan. While I primarily strive to produce an interesting and captivating image from an aesthetic point of view the scientific value (if any) is certainly on my mind when it comes to images like this one.
For example the Intracluster Light seems to not have been descibed in literature before (see my reply to Mike above)
Quote:
Originally Posted by Shiraz
This is a wonderful effort Rolf. Thanks so much for posting your results and the very interesting and illuminating associated write-up .
Thanks a lot Ray. Speaking of illumination, it would be interesting to calculate the total (nano)Watt hours picked up by the CCD for this image!
Quote:
Originally Posted by Slawomir
Awesome, unique, inspiring...think you Rolf for sharing the fruits of your hard work. I will need to read your write up again, slowly, and I will be enjoying coming back to your image to watch it, soak it in and to appreciate it.
Thanks for your kind words Slawomir, enjoy the image there is a lot going on in the background as well, distant galaxy clusters etc.
Quote:
Originally Posted by troypiggo
Spending that amount of time gathering imaging data is one thing, and that's huge. But the amount of work you've put into the supplemental information and writeup - to a noob like me - that looks like a PhD submission! The combination of both is absolutely monumental. Hard to believe, but you've exceeded your previous attempts by a mile. I have no idea where you can go from here, but looking forward to it!
PS - I'm off to read more on intracluster light. I'm familiar with IFN etc, but not IcL.
PPS - I'm interested to know more about the data acquisition philosophy on such a huge amount of data on a night by night basis. You mention 4-5hrs data collected each night, but it's hard to tell from your graph whether you'd do all L in one night, all R in another night etc, or if you gather less subs of all LRGB in the same night?
Thank you Troy About data acquisition, I gave preference to luminance data whenever the Moon was not too bright and seeing was reasonable (Reasonable being somewhat arbitrary ). You can see the different bars on the graph jumping accordingly. For colour I took significantly more R than G/B because the faintest galaxies tend to be red and moonlight doesn't brighten the sky much in R, except for a few days right at full Moon. G and B data still had to be limited to moonless nights though.
Quote:
Originally Posted by multiweb
Sublime picture Rolf. That's dedication. Excellent write up. Learnt a lot. Will have to come back and read and look again. That's a lot to take on.
Thanks very much Marc, glad you liked the write up too!
Quote:
Originally Posted by Paul Haese
Huge body of work Rolf and I cannot help feeling that 60 hours of that time could have been put toward another project. Law of diminishing returns would be applicable here.
The medium image is superb looking with lots of things to view and inspect. It looks very well processed. Great colour saturation and very nice detail in all the major spirals and despite my above opinion massive amounts of signal acquired. Without doubt a reason why mega data collection is a good thing, despite some critics thinking signal acquisition is ok for some and not for others.
When I went and looked at the high res version one on your site whilst it was smooth it had the appearance of being smoothed in some way. Maybe this is not the case but that is how it looks on my monitor. Some of my longer galaxy projects give this appearance if I apply some smoothing to the background. The stars also look a little odd, but those are very minor things compared to the overall effect of the image.
I suspected this was the region you were imaging that night we had that discussion many months ago of what you were imaging next. I spent a bit of time looking around and thought in the end this must have been your target.
I don't agree that this is a boring area at all. The differing types of galaxies present and the super nova remnant make for a very interesting looking image and well worth imaging.
In my opinion a very nice looking with loads of detail and interest. Certainly close to one of your best and worthy APOD should you obtain that. You have now inspired me to add this to my imaging list. Well done Rolf.
Thanks for your kind feedback Paul. Re stars, yes in the corners there is a bit of distortion still which is a result of the Baader MPCC having very little tolerance as to collimation and tilt in order to produce perfect stars across the entire frame. This is something that has annoyed me more and more, and I've actually now replaced it with a Paracorr so watch this space
There is no smoothing as such applied, other than a bit of light noise reduction with a luminance mask. I did experiment with the sharpness of the stars though and found that their somewhat toned down appearance here is better suited for the presentation of the IcL and IFN structures which was something I really wanted to highlight with this image. Perhaps I'll revisit that in a future repro
As for the time spent, I don't think I could have brought out this level of deep detail with significantly less exposure time, as the integration progress collage shows. But of course diminishing returns do apply at some stage.
Hats off to you Rolf, tremendous dedication and hard work to make a truly unique image.
I also am floored about your 500 darks and 300 flats - oh my god. I would love to see an example of a light calibrated with a regular say 6 set of flats and one with the 300, same with the 500 darks. Does it make much difference?
Those little galaxies are amazing and that dark spot on the inner side of the ring of that galaxy is very odd. It looks a bit like a dark hole. I wonder if it has a small dark hole there.
Greg.
Thanks so much Greg. About the darks/flats, they do add noise to the final stacked image so it's important to keep the master dark/flat as clean as possible. I can imagine using only 6 darks/flats would add quite a lot of noise to the final result! I did an experiment to test this a while back and could clearly both measure and see the difference. Taking several hundred darks and flats may seem like a lot of effort, but it's only once every six months or 1 year (I last updated my calibration library in Dec 2014).
With PixInsight's SuperBias script you can even create a synthetic master bias frame which is completely noise free. I used the script to create mine from 500 bias frames, which may be overkill - but at least bias frames are quick to acquire.
Quote:
Originally Posted by clive milne
There is a lot to like about what you have done there Rolf (much of it already stated by others)
However, in the spirit of constructive criticism and in an attempt to apply the scientific method even at the philosophical level, there is not much to be learned through validation. So, I'll keep my comments to what I believe to be the area's which might be improved.
It is my opinion (and take that as you wish) that the limit of your rig is a product of the light (from the foreground stars) being scattered across the fov from the various optical surfaces in the OTA, including internal reflections. There are a number of ways to reduce this issue.
* Image areas of the sky which are far away from the galactic plane.
* Switch optical trains to minimise scattered light. (I suspect the good old RC design without a field flattener might enable you to go deeper still)
best
c
Thanks for your feedback Clive. You're probably right that a RC with less optical surfaces would allow slightly deeper images for the same integration time. However, that would require a significant investment in more expensive optics and new camera etc to match. A more capable mount would also be necessary to handle the heavier OTA. I did consider the RC design when building my OTA, but decided it's hard to beat the efficiency, simplicity and cost effectiveness of a fast Newtonian with premium optics. That said, I'm sure there's another scope waiting for me sometime in the future so we'll see
Quote:
Originally Posted by JD2439975
(Humbly kneeling before Zod).
LOL, cheers Justin!
Quote:
Originally Posted by scagman
Awesome image.
Thanks a lot John!
Quote:
Originally Posted by el_draco
That's a BIG FAT DITTO from me....
Thanks Rom
Quote:
Originally Posted by Octane
Does it get any better than this?
The image, write-up, tid bits, presentation, etc., all world class.
You the man, Rolf.
H
Thank you H, I'm glad you liked it all, I do try to put an effort into both the image and the presentation. It's nice to be able to tell an interesting story and bring the subject matter to life - and we're fortunate that nearly everything about deep sky objects is fascinating!
Quote:
Originally Posted by plantnerd
WOW such an exceptional image very inspiring for me personally just setting up my observatory with 10" Newt to show what can be achieved and to strive for perfection.
Gets my vote for APOD.
Thanks a lot Luis, and good luck with your observatory!
Quote:
Originally Posted by DavidU
Thanks Dave
Quote:
Originally Posted by Regulus
Speechless Rolf.
Trev
Thank you Trev
Quote:
Originally Posted by topheart
Wonderful stuff.....!!
Thanks very much!
Tim
Thanks Tim, you're welcome!
Quote:
Originally Posted by SamD
Hi Rolf, as many have said, great work !
Yes, it can be difficult to pick out any Intracluster light from the Integrated Flux Nebula. I've aligned a (linearly stretched) image from the WISE survey (12um W3 band) which may help.
In the survey image you can see many faint bands and patches, including a slightly brighter patch to the right of NGC 3258, which may confuse the identification of a intracluster bridge to the NGC 3268 group.
Based on the published radial velocities in the Principal Galaxies Catalogue and measuring the angular distances between NGC 3258 and 3268, these two galaxies are probably 1-2 million light years apart, so there could well be a stellar stream between them. There's quite a large difference (about 1000km/s) between the radial velocities of NGC 3258/3268 and 3269 which would normally mean that NGC 3269 is about 50Mly further away. However, it's more likely though that the large difference in radial velocity is just relative motion within the cluster, so there could also be a faint intracluster bridge between these galaxies too.
Thanks very much Sam for the comprehensive info. I hadn't noticed the discrepancy in radial velocity between NGC3258/3268 and NGC3269, that's interesting. I don't know if the IcL extends to 3269 as it's impossible to see with the IFN interfering. It could be either or. Regarding the distance, I imagine NGC3269 is a member of the cluster and must be at a similar distance as 3258/68, because otherwise it would be an unusually large spiral if it's 50M light years further away.
Quote:
Originally Posted by graham.hobart
Humbling Rolf, and an exceptional presentation.
Lots to see and learn
Thanks for sharing this wonderful project
Graz
Thanks Graham, it feels like a Hubble deep field with all the distant galaxies there and that is very humbling indeed. It's a big Universe!
Quote:
Originally Posted by IanP
Rolf, hats off to you
Definitely an APOD winner !!!
Thank you Ian, hard to know about APOD there are so many great images to choose from these days.
Quote:
Originally Posted by AstroJason
That is just incredible, simply stunning Rolf!!
Thanks very much Jason!
Quote:
Originally Posted by Rex
Awesome project Rolf! Great write up and wonderfully deep image. Thanks for sharing mate, Top Notch all the way.
Thank you for the kind comment Rex
Quote:
Originally Posted by jase
Impressive to say the least Rolf. Enjoyed the write up and comparative images. I have few questions;
Thanks very much Jase, I'll answer your questions below:
Quote:
Originally Posted by jase
What was your methodology for combining such a large stack of sub frames? Did you group them into smaller masters, then combine the masters? I'm using PixInsight now, which handles large stacks without issue. I have had to stack in batches in the past though (e.g. for 120 hours Cen A) because Maxim ran out of memory.
What was your FWHM tolerance for including a sub into the combine? You show a FWHM of 1.7" in one I didn't use a particular FWHM tolerance but only rejected subs where the stars were trailed, or excessively blurred by wind/bad tracking. I left it up to PixInsight to combine the frames based on noise levels - the frames with larger FWHM tend to also have higher noise so end up contributing comparatively less.
If you've used 152hrs, what percentage did you trash due to not meeting the tolerance? As above, not that much rejected really. I think maybe <5% all up.
Do let us all in on your secret on how to capture quality LRGB data 2 days before full moon on the 4th April with an 12.5" F/4 scope! Se my reply to Troy further up. On 2nd April I only took a few L frames and 1 hour of R data. In R band sky brightness is not as affected by Moon light as it is in B, see for example http://www.tng.iac.es/info/la_palma_sky.html
Did you consider binning the RGB data given its not delivering any further resolution compared the Lum? Would have saved you some exposure time. I used to take my RGB binned 2x2 but have gone 1x1 for the past year or so. I found that it gives better colouring of stars and the ability to create a synthetic luminance frame and add it to the real luminance is a bonus. There is a noticeable difference in S/R with the added synthetic L and I do that with all my images now.
Quote:
Originally Posted by PRejto
Bravissimo!
Your dedication has resulted in a spectacular image. Thanks very much for posting the luminance stacking results. Most interesting! Like Jase I am very curious about your methodology for dealing with such a large data set.
Thanks,
Peter
Thanks very much Peter, see reply to Jase above
Quote:
Originally Posted by lazjen
Impressive image and a great write up. Congrats.
This was done in Auckland? How much light pollution do you have?
Thank you Chris. Yes I'm in Auckland, in the outer suburbs away from most of the light. My skies are 20.3 SQM which I think translates to Bortle ~5.
Herculean effort Rolf! The result is outstanding and I do agree, the write up and all the job done on comparison with other images add a lot to an already unique image, bravo!
Marco
so thank you for doing the hard yards (understatement) and producing a deep and intriguing vista 
