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Old 19-09-2019, 08:57 AM
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An experiment in deep integration

I am currently working on NGC55 and have spent a bit of time examining the Ha and luminance data. Images I have seen on the web don't appear to show some things I have noticed in the Ha data. I suspect this is because the amount of integration is smaller than I have collected so far. Or this data is so faint that it just does not show through when combined with the brighter LRGB data.

So far I have taken 510 minutes of Ha and only 20 minutes of luminance. The Ha is the most interesting to me. Near the central core I can now see some very large loops which extend out a little from the top and bottom of the lanes. There are also many small bubbles along the entire length of the galaxy which are quite faint and these have become more visible with increasing integration. My plan is to increase integration to see if I can make these faint objects visible in an integrated image. I don't think I will do 50 hours on the Ha, however for now I will do double of what I have and then see how much more definition I can get. I'll also go fairly deep on the LRGB too to bring out the faint background galaxies and to give a very pleasing colour image.

My thinking here is that all my best images have had colour data greater than 4 hours per channel and with very deep luminance. In fact nearly all my images with greater than 30 hours present cleaner and more vibrancy. I have noted over the years that guys such as Rolf Olsen take a similar approach which has confirmed my thinking.

I think this is an interesting experiment, perhaps showing the gas loops for the first time. I have included both Ha and luminance images for comparison.

Feel free to discuss.
Attached Thumbnails
Click for full-size image (NGC55 Lum 20 cr.jpg)
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Click for full-size image (Sum NGC55 510 Ha 1 cr.jpg)
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Old 19-09-2019, 09:26 AM
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Great images Paul,

Look forward to the end product.

p.s. recently viewed NGC55 through the ASV's 40" scope and the "clumps" in your Ha image were very evident through a UHC filter!
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Old 19-09-2019, 09:49 AM
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This is very interesting and worthwhile Paul. I recall a talk by Jay Gabany at the AAIC where he demonstrated surprising features revealed by ultradeep exposures (I think you were there too). I think there may be a lot of unexpected stuff out there.
Geoff
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Old 19-09-2019, 01:46 PM
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Ultra deep exposures are the way to go especially if you have done lots of imaging and don't have the "got to image the next object bug".

The hard part here Paul will be blending the Ha into the LRGB and retaining those Ha details. I find a lot of the Ha detail goes missing when its blended in to RGB and if you try to set Ha as luminance it makes salmon colours.

Greg.
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Old 19-09-2019, 02:08 PM
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strongmanmike (Michael)
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Yes well, longer exposures'll do that....

Looks almost identical to my Ha data on the object taken exactly a year ago, almost like it was taken with the same scope

Mike
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Old 19-09-2019, 02:28 PM
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Thanks guys for the comments and discussion.


Quote:
Originally Posted by Geoff45 View Post
This is very interesting and worthwhile Paul. I recall a talk by Jay Gabany at the AAIC where he demonstrated surprising features revealed by ultradeep exposures (I think you were there too). I think there may be a lot of unexpected stuff out there.
Geoff
Yes I was there, Jay is an advocate for plenty of data and heaps in colour.

Quote:
Originally Posted by gregbradley View Post
Ultra deep exposures are the way to go especially if you have done lots of imaging and don't have the "got to image the next object bug".

The hard part here Paul will be blending the Ha into the LRGB and retaining those Ha details. I find a lot of the Ha detail goes missing when its blended in to RGB and if you try to set Ha as luminance it makes salmon colours.

Greg.
The hard part is remaining focused on the task Greg. I just keep setting the amounts I need and do a bit of processing in each filter once in a while to see how things are going. When I did the Helix with 111 hours I just keep processing the Ha and OIII data to see what was changing. Unfortunately I lost the urge to keep going and failed to produce anything like Suavi's image recently.

Agreed, that Ha can go missing. I am planning on using the lighten mode and colourisation technique to show the Ha data. When it is bright it really shows up well.


Quote:
Originally Posted by strongmanmike View Post
Yes well, longer exposures'll do that....

Looks almost identical to my Ha data on the object taken exactly a year ago, almost like it was taken with the same scope

Mike
We'll not exactly the same scope but same model. Minus the corrrector Though your image is a lot bigger than mine too, I take it your resampled. Your data was about 150 minutes but you were using the 694 sensor, which was more sensitive to hydrogen I believe. This was done with the 8300 I have in the QSI. I have a 694 in an Aluma but it is not fitted to the scope at present. So this data is not quite as sensitive as what your sensor can achieve at the same integration. Did you see the jets coming out of the core there? Top and bottom? I cannot see them in your combined image but they might be there in the Ha. Feel free to post your Ha here for interest.
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Old 19-09-2019, 02:44 PM
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No not resampled, that is just the full res jpeg on my PBase site.

Yes the faint Ha filaments are visible in my 150min Ha but a couple of'em are ever so slightly easier to distinguish in your longer exposure but there is nothing in it really. The visibility of fine features in the Ha across the galaxy is essentially the same, so your current corrector would seem to be working as well as mine.

I combined my Ha with the Red, so yes, the fainter extensions of pink-red Ha are a little suppressed in my final L(HaR)GB, which was just a processing choice for a more natural looking final result.

Mike
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Old 19-09-2019, 05:26 PM
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I take it the data is post servicing mission, as the stellar profiles and nice and tight.

Blending h-alpha is a bit of an art, but without doubt there is merit in using it to highlight a galaxy's star forming regions.
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Old 20-09-2019, 09:10 AM
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Quote:
Originally Posted by strongmanmike View Post
No not resampled, that is just the full res jpeg on my PBase site.

Yes the faint Ha filaments are visible in my 150min Ha but a couple of'em are ever so slightly easier to distinguish in your longer exposure but there is nothing in it really. The visibility of fine features in the Ha across the galaxy is essentially the same, so your current corrector would seem to be working as well as mine.

I combined my Ha with the Red, so yes, the fainter extensions of pink-red Ha are a little suppressed in my final L(HaR)GB, which was just a processing choice for a more natural looking final result.

Mike
That would be the 0.12" of image scale then. It just seemed a lot bigger than my image. Although I am imaging at f4 and the primary on mine is 296mm, so this would also play a part.
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Old 20-09-2019, 09:20 AM
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Quote:
Originally Posted by Peter Ward View Post
I take it the data is post servicing mission, as the stellar profiles and nice and tight.

Blending h-alpha is a bit of an art, but without doubt there is merit in using it to highlight a galaxy's star forming regions.
I have decided not to use the serviced corrector anymore. I have found whilst is works ok it is not to my personal liking. Star profiles are not as tight and it is very finicky to get the space exactly right across the field. Currently I am using a GPU and have also bought a paracorr which I will use with the Aluma camera I bought a few months back.
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Old 20-09-2019, 06:49 PM
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Quote:
Originally Posted by Paul Haese View Post
I have decided not to use the serviced corrector anymore. I have found whilst is works ok it is not to my personal liking. Star profiles are not as tight and it is very finicky to get the space exactly right across the field. Currently I am using a GPU and have also bought a paracorr which I will use with the Aluma camera I bought a few months back.
Bummer about the corrector.

Aluma's look very interesting. A few have passed by me, but I've not had a chance to tinker with one.

But where to go next with sensors? Sony CCD's look quite seductive, but I suspect they are not a game changer.

eMCCD's look awesome, as do their price tags.

But once we have sensors with bugger all noise and superb QE, it will come back to the optics & mount....and sorry, I digress....no doubt the Aluma with a fast Newt is a good start!

Last edited by Peter Ward; 20-09-2019 at 07:48 PM.
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Old 02-10-2019, 09:06 AM
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A bit of an update on this imaging run.

So far I have 580 minutes of Ha data and 495 minutes of luminance. The annotated luminance image attached shows that there are a lot of fainter background galaxies showing through, however there are many that are not being picked up by the catalogs I selected. Some of those that have been selected are around mag 20, so I am assuming that the smaller fainter ones are getting around Mag 22-24 or fainter. I am also starting to see what appears as a extended halo to the NGC55 too. I will keep plugging away to determine if it goes any further out. Doubling of the data should show that.

The Ha data is looking pretty good now, with the fainter jets and loops showing a bit easier, however they are not bright enough yet to show up in a colour image. Again, a doubling of the data should give greater clarity. The bubbles and knots are also very interesting to look at in the Ha data.

So for now I keep persisting.
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Click for full-size image (Sum_NGC55_495_Lum_cs_Annotated final 4 scaled.jpg)
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Click for full-size image (Sum NGC55 580 Ha cs 1.jpg)
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Last edited by Paul Haese; 02-10-2019 at 02:44 PM.
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Old 03-10-2019, 05:50 PM
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The detail is starting to show up quite nicely already, and it is such a tough target to image! Wishing you many clear nights so we will get to admire a fantastic ultra deep image of this galaxy
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Old 05-10-2019, 08:36 AM
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Suavi, I am up to 900 minutes on the Ha now but must stop collecting now due to the waxing moon. Cloud forecast for the next week is not favorable for collection either. If I am lucky I might get a few hours here and there in the next week. Next month I'll collect more though and continue onward.
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Old 18-10-2019, 07:28 PM
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Update:

I am up to 18.5 hours now on the Ha. Certainly some improvement from the first image. The loops are now visible in the core area. Not really bright but certainly brighter and more pronounced than before.There is also so much more to see in the individual bubbles of gas throughout the galaxy. Still more to collect yet. I am aiming to have all the bubbles really bright and visible. I imagine that I am only collecting a few photons per hour for several of these spots on the outer regions. The more learned amongst us might be able to confirm this theory.
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Old 18-10-2019, 08:19 PM
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Sounds like a fascinating and rewarding project Paul
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Old 18-10-2019, 09:40 PM
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The H-alpha image is splendid. The giant loops are inspiring, awesome. Well done.
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