Tulip nebula

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JR

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Oct 3, 2021, 9:35:16 AM10/3/21
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Friday night. Managed 15 exposures but the last 4 were poor, perhaps with the next lot of rain advancing.

ZWO one shot colour asi533 mc, -10C, 384s each, unguided, at gain 100 (as recommended by Sharpcap sensor analysis and sky darkness measurement), Optolong l-extreme filter (7nm passbands), Esprit 80ed f5/400, Lakeside autofocuser.

Workflow: Pixinsight blink image inspection, DSS stacking of 11 .fits (Σ1hr:10m) with flats and bias (matched darks produced very odd effects for no reason I can find), Pixinsight linear data phase with temporary stretch, background extraction, green reduction, channel equalisation, basic noise reduction; non linear phase permanent stretch, curves.

If I have more time to return to the data I'm sure better results are possible. Colours need refining, noise still an issue, (may try redoing darks), and I couldn't get star removal to work making it easier to adjust the background and nebula - 'It goes on for ever, it's full of stars' to quote Bowman in the 2001 Space Odyssey! Doing something wrong with the masks.

image1.jpeg

William Bottaci

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Oct 12, 2021, 8:18:40 AM10/12/21
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Hello James, despite your reservations this is a worthy effort; I like it. Yet another suggestion for 'us' to have a go at this object.
You've also captured Cygnus X-1, the strongest X-ray and the first such source believed to be a black hole - bottom of the tulip and left about a couple of inches (at 100%).

Yes, the noise is visible, and wondering why. Perhaps it's the low number of exposures; the filter being narrow band does extend the length of each exposure. Not including darks would also contribute of course, a shame about them.
Could I suggest something? The people over at DSS suggest that if using a CMOS rather than CCD sensor then using dark flats will give better results than bias frames; because you're otherwise subtracting a calibration frame twice, negating it's affect. I can, 'offline', give the explanation; it's technical.
Dark flats are easy; exactly the same as darks but with the lens cap on, change nothing else, and they're also quick.

As for colour, not sure about refining. Half of people like it as it is, and the other half are never satisfied (my little insight into human nature :).

Your workflow sounds, how can I put this, sensible? It lists as you're doing all the right things, and any weakness in the results seems, to me, to not having enough data. Definitely worth revisiting, and with your filter the Moon won't be as much of a hindrance.

Nearly forgot, the method you use to estimate exposure, is this the SharpCap Smart Histogram? Kevin and I are looking to try that next; long overdue.

Thank you for sharing.
William
James

Kevin Phillips

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Oct 12, 2021, 8:38:27 AM10/12/21
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Tim what a great capture.  Something I would like to di sone day. Thank you for sharing. I could do with some tips on processing.


From: croydo...@googlegroups.com <croydo...@googlegroups.com> on behalf of William Bottaci <w.bo...@gmail.com>
Sent: Tuesday, October 12, 2021 1:18:22 PM
To: croydo...@googlegroups.com <croydo...@googlegroups.com>
Subject: [croydonastro - 7034] Tulip nebula
 
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Kevin Phillips

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Oct 12, 2021, 10:11:34 AM10/12/21
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I made a mistake credit ti James  for the beautiful capture of the tulip nebula. We truly have some amazing astrophotographer here at tge CAS. Thank you for your efforts James
From: croydo...@googlegroups.com <croydo...@googlegroups.com> on behalf of Kevin Phillips <thewels...@live.com>
Sent: Tuesday, October 12, 2021 1:38:24 PM
To: croydo...@googlegroups.com <croydo...@googlegroups.com>
Subject: Re: [croydonastro - 7035] Tulip nebula
 

JR

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Oct 13, 2021, 4:01:11 AM10/13/21
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Hi Kevin

No problem.  I'm very flattered you might think it was by Tim.  But as you can see from John Mills image of the Tulip a lot better is possible and I'm sure Tim would also far surpass my result.

Imaging for me is a combination of 'the picture' and its technical perfection.  You'd like both, but a picture creates an artistic response that can go a long way to forgive imperfections.  How many popular singers have operatic voices?

In my Tulip, I like the mirky foreground lit up by the flower.  The universe is more dark than pretty, (in more than one way).  I didn't rotate the image to show the object as it would be seen.  This preserves what looks like a 3D serpent of a roiling gas cloud headed this way, at the bottom of the image, otherwise lost.

James

Sent from my iPad

On 12 Oct 2021, at 15:11, Kevin Phillips <thewels...@live.com> wrote:



Kevin Phillips

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Oct 13, 2021, 4:30:44 AM10/13/21
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You lot better than myself so all credit gose to you. I only started image properly last September 2020. There is so much learn processing for me is still a bit if an issue but I have improved since last year.  I will have a go at that object see how it comes out. Thanks buddy 
From: 'JR' via croydonastro <croydo...@googlegroups.com>
Sent: Wednesday, October 13, 2021 9:01:01 AM
To: croydo...@googlegroups.com <croydo...@googlegroups.com>
Subject: Re: [croydonastro - 7039] Tulip nebula
 

JR

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Oct 13, 2021, 5:31:41 AM10/13/21
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Hi William

Thank you for your comments and helpful thoughts and suggestions.  The processing is tricky but as you suggest, there are many possible interpretations that make it a rewarding target if others wanted to try.

I didn't know I'd captured a black hole.  Pity you can't see them!

I still don't know why the darks didn't work.  I didn't know about using dark flats rather than bias and will certainly try that.

I'm finding that Pixinsight workflows take on a pretty much fixed sequence.  Each process has a screen icon when you open it.  People stack these down the right hand side of the screen.  They record what you did and you can save the sequence for next time.   A screen shot of the icons is all you need to see how someone else got their results.  

There is a delight in the grandiose description, auto stretch is for example the Screen Transfer Function, not to mention a lot of 'deprecating' with dire warnings should you do some things rather than others.  But underneath is a solid logic.  Process divides into working on unstretched data to enhance the signal, followed by a cosmetics phase working on the stretched.   And if there's something you want to do, it's there and works well.

The foothills that are the hardest to get up, when you are entirely new to it.  It's like cookery books that start a recipe with 'make pastry', at which point, I at least am scuppered.

I did use the Sharpcap smart histogram to determine exposures.  You get guided through the one off process.   The info is saved for you and available whenever you connect the camera.  You take an exposure of the night sky as a prelude to an imaging session and Sharpcap works out the best settings given your recorded level of light pollution.  

Worth doing though some discretion is needed.  For instance, few long exposures rather than many short may be fine for faint detail with dark skies, but they tend to bloat stars. 

regards 

James

Sent from my iPad

On 12 Oct 2021, at 13:18, William Bottaci <w.bo...@gmail.com> wrote:


--

William Bottaci

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Nov 1, 2021, 8:20:16 AM11/1/21
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A late reply but thank you for the response and advice. I've also noted what you've said about using the SharpCap Smart Histogram, thanks.

And to point out the deliberate mistake, regarding taking dark flats instead of bias frames if using CMOS sensors; substitute the word 'darks' with 'flats', so that the sentence should read:
--
Dark flats are easy; exactly the same as 'flats' but with the lens cap on, change nothing else, and they're also quick.
--
else it wouldn't make sense.
Errors should be corrected. Of course you noticed it, but I thank you for not pointing it out :}.

William




On Wed, 13 Oct 2021 at 10:31, 'JR' via croydonastro <croydo...@googlegroups.com> wrote:
Hi William
Thank you for your comments and helpful thoughts and suggestions.  The processing is tricky but as you suggest, there are many possible interpretations that make it a rewarding target if others wanted to try.

I didn't know I'd captured a black hole.  Pity you can't see them!

I still don't know why the darks didn't work.  I didn't know about using dark flats rather than bias and will certainly try that.

I'm finding that Pixinsight workflows take on a pretty much fixed sequence.  Each process has a screen icon when you open it.  People stack these down the right hand side of the screen.  They record what you did and you can save the sequence for next time.   A screen shot of the icons is all you need to see how someone else got their results.  

There is a delight in the grandiose description, auto stretch is for example the Screen Transfer Function, not to mention a lot of 'deprecating' with dire warnings should you do some things rather than others.  But underneath is a solid logic.  Process divides into working on unstretched data to enhance the signal, followed by a cosmetics phase working on the stretched.   And if there's something you want to do, it's there and works well.

The foothills that are the hardest to get up, when you are entirely new to it.  It's like cookery books that start a recipe with 'make pastry', at which point, I at least am scuppered.

I did use the Sharpcap smart histogram to determine exposures.  You get guided through the one off process.   The info is saved for you and available whenever you connect the camera.  You take an exposure of the night sky as a prelude to an imaging session and Sharpcap works out the best settings given your recorded level of light pollution.  

Worth doing though some discretion is needed.  For instance, few long exposures rather than many short may be fine for faint detail with dark skies, but they tend to bloat stars.
regards
James



On Wed, 13 Oct 2021 at 09:01, 'JR' via croydonastro <croydo...@googlegroups.com> wrote:
Hi Kevin
No problem.  I'm very flattered you might think it was by Tim.  But as you can see from John Mills image of the Tulip a lot better is possible and I'm sure Tim would also far surpass my result.

Imaging for me is a combination of 'the picture' and its technical perfection.  You'd like both, but a picture creates an artistic response that can go a long way to forgive imperfections.  How many popular singers have operatic voices?

In my Tulip, I like the mirky foreground lit up by the flower.  The universe is more dark than pretty, (in more than one way).  I didn't rotate the image to show the object as it would be seen.  This preserves what looks like a 3D serpent of a roiling gas cloud headed this way, at the bottom of the image, otherwise lost.
James



On Wed, 13 Oct 2021 at 09:30, Kevin Phillips <thewels...@live.com> wrote:
You lot better than myself so all credit gose to you. I only started image properly last September 2020. There is so much learn processing for me is still a bit if an issue but I have improved since last year.  I will have a go at that object see how it comes out. Thanks buddy



On Tue, 12 Oct 2021 at 15:11, Kevin Phillips <thewels...@live.com> wrote:
I made a mistake credit ti James  for the beautiful capture of the tulip nebula. We truly have some amazing astrophotographer here at tge CAS. Thank you for your efforts James



On Tue, 12 Oct 2021 at 13:38, Kevin Phillips <thewels...@live.com> wrote:
Tim what a great capture.  Something I would like to di sone day. Thank you for sharing. I could do with some tips on processing.



2021-10-12

Hello James, despite your reservations this is a worthy effort; I like it. Yet another suggestion for 'us' to have a go at this object.
You've also captured Cygnus X-1, the strongest X-ray and the first such source believed to be a black hole - bottom of the tulip and left about a couple of inches (at 100%).

Yes, the noise is visible, and wondering why. Perhaps it's the low number of exposures; the filter being narrow band does extend the length of each exposure. Not including darks would also contribute of course, a shame about them.
Could I suggest something? The people over at DSS suggest that if using a CMOS rather than CCD sensor then using dark flats will give better results than bias frames; because you're otherwise subtracting a calibration frame twice, negating it's affect. I can, 'offline', give the explanation; it's technical.
Dark flats are easy; exactly the same as darks but with the lens cap on, change nothing else, and they're also quick.

As for colour, not sure about refining. Half of people like it as it is, and the other half are never satisfied (my little insight into human nature :).

Your workflow sounds, how can I put this, sensible? It lists as you're doing all the right things, and any weakness in the results seems, to me, to not having enough data. Definitely worth revisiting, and with your filter the Moon won't be as much of a hindrance.

Nearly forgot, the method you use to estimate exposure, is this the SharpCap Smart Histogram? Kevin and I are looking to try that next; long overdue.

Thank you for sharing.
William



On Sun, 3 Oct 2021 at 14:35, 'JR' via croydonastro <croydo...@googlegroups.com> wrote:
James
image1.jpeg

Kevin Phillips

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Nov 4, 2021, 6:22:28 AM11/4/21
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That is beautiful, that could be My next project. Using tge histogram on sharpcap will be my next project. 
Kevin 
Sent: Monday, November 1, 2021 12:19:55 PM
To: croydo...@googlegroups.com <croydo...@googlegroups.com>
Subject: [croydonastro - 7049] Tulip nebula
 
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trevsie7

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Nov 4, 2021, 9:44:39 AM11/4/21
to 'J R' via croydonastro
Hi James,
That is a good image and looks very promising.

I have recently purchased Pixinsight now that the post-Brexit price is lower and am gradually coming to terms with its quirky (but powerful) user interface.
Just wondering why you used DSS to stack the images rather than the Pixinsight batch processing script (i.e. SCRIPT>Batch processing>WeightedbatchPreprocessing)? I find this gives excellent results with narrowband, though I haven't tried to use it for one-shot colour images.


JR

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Nov 6, 2021, 4:12:30 AM11/6/21
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Thanks Trevor.  

When I first got Pixinsight, getting to grips with post stacking processing was sufficient unto the day and stuck with DSS.  I subsequently tried the Pixinsight process on the same data but couldn't see any difference, so continued to keep with DSS.  DSS also seems to have upped its game recently (or maybe I now understand the documentation better), and compared to PI, feel I have a better insight into what it's doing and a clearer understanding for making choices on options.

I'd nevertheless be very interested to know if you've managed to obtain a significant improvement using PI!

I'd add that my laptop flies through stacking using DSS and is noticeably faster than Pixinsight using the same data, (Intel I7 11th generation, 1TB SSD and 16Gb of Ram so probably not the hardware that accounts for the speed difference)

regards

James



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On 4 Nov 2021, at 13:44, trevsie7 <trevs...@gmail.com> wrote:


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