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The Core of the Rosette Nebula

steppenwolf

By steppenwolf
in Imaging - Deep Sky

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steppenwolf

steppenwolf

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The Rosette Nebula (WIP)

The Rosette Nebula is a region of intense star formation. The stellar winds from the young stars within the nebula exert a high pressure on the interstellar clouds, compressing them and it is this compression that leads to ongoing star formation.

There are several obscuring dark veins of matter (not to be confused with ‘veins of dark matter’!) within the nebula. Close examination of these veins reveals tiny dark blobs of matter. These dark blobs are known as Bok Globules after the Dutch born Harvard Professor Bartholomeus (Bart) Jan Bok. Bok suggested that the globules were at one time attached to umbilical filaments of neutral Hydrogen gas. Radiation from local stars first separated and then compressed the filaments leaving individual small areas of matter that continued to contract under the pull of their own gravity until they formed the globules visible today. It is believed that these globules contain primeval dust clouds from which new stars are being formed.

I have a long way to go with this image and unfortunately, the clouds have just killed my data acquisition for tonight but the result with just 4.3 hours of data is looking promising. Having examined the field of view, I might well re-frame the project to concentrate more on the Boks and just let the core become off-centre!

Image Stats

Mount: Mesu 200
Telescope: Sky-Watcher Esprit 150
Flattener: Sky-Watcher Esprit specific
Camera: QSI 683 WSG-8
Filter: Astrodon 3nm Ha
Subframes: 13 x 1200 sec Ha
Integration: 4.3 hours
Control: CCD Commander
Capture: MaxIm DL
Calibration and Stacking: PixInsight
Post-Processing: PhotoShop PS3

integration_Rosette_Ha_13_decon.thumb.png.90e6c8db4b61a7b80c275de30320cc55.png

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PhotoGav

PhotoGav

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Looking very promising, Steve. I think your reframing idea is a good one. Nudge the line of Bok Globules up a bit and you’ll catch the whole string of them. The whole approach of processing data mid project is a very worthwhile exercise as it can hugely influence the project in a positive direction before it’s too late to change. I used to wait until I had collected every last sub before touching the data, but nowadays I have moved to APP for integration and it is so simple that I am starting to look at how things are going after each collection session and making changes along the way as a consequence. Good luck with the continuing project and clear skies - which I think could be at a premium for the next while!

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Barry-Wilson

Barry-Wilson

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A terrific Ha study Steve as it currently stands - and a very promising beginning to a HST image.  Very sharp.

I agree with your suggested re-framing.  The eye is naturall drawn to the Bok globules because of their familiarity to animals.  Whilst you might ultimatley frame 'less' of the central portion of the Rosette, your composition will gain in interest and impact I think.

Looking forward to the next instalment . . . not promising weather at the moment though.

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steppenwolf

steppenwolf

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10 hours ago, alan potts said:

it is a shame you don't have my sky and amount of clear one.

Yes, I could REALLY do with some decent skies here or rather skies that don't cloud over so much!

7 hours ago, PhotoGav said:

The whole approach of processing data mid project is a very worthwhile exercise as it can hugely influence the project in a positive direction before it’s too late to change.

I normally examine the first sub out for framing but having set the session going, I got involved in something else! My goal here was always the 'core' but that cut off Bok at the base of the image is a shame!

6 hours ago, ollypenrice said:

What makes this image is the tiny star size, letting the nebulosity give some impression of its mind boggling real size. Are you pleased with the Astrodon, Steve?

I think I can guess the answer...

The extremely narrow filter does make it a lot easier to control the stars and let the nebulosity stand out. Oh yes, I love my Astrodon. I keep wondering if I made the right decision going for the 3nm over the 5nm but then a relatively small amount of data in a mediocre sky produces some nice crisp detail and I know that I made the right decision for me.

6 hours ago, kirkster501 said:

That 3nm Astrodon is quite soemthing (as it should be for the £££££?)

They do know how to charge don't they? However, the high percentage of transmittance at the emission wavelength (guaranteed 90% but often higher) is very difficult to achieve and this is reflected (ooops pun) in the cost.

44 minutes ago, Barry-Wilson said:

Whilst you might ultimatley frame 'less' of the central portion of the Rosette, your composition will gain in interest and impact I think.

Thanks Barry, my thoughts entirely - sadly as that is nice data to reject!

Thanks for your other comments folks!

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steppenwolf

steppenwolf

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1 hour ago, Petergoodhew said:

Gorgeous tight stars Steve..  Yes I can see those Boks crying out for centre stage!  I await the final result with great interest.

Thanks, Peter, it was your gorgeous image of the centre of the Rosette that made me consider taking a close-in set of it with the Esprit 150 - I normally think of this object as being a wide-field one but your image convinced me otherwise!

17 minutes ago, swag72 said:

That looks great Steve..... I do agree about a re-frame though to get all of those Bok globules in ?

Thanks, Sara

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PhotoGav

PhotoGav

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10 hours ago, steppenwolf said:

The 5nm allows some NII signal through!

But is that really a good thing?!

I am very interested in your choice of 3nm over 5nm and your image of the Rosette is a stunning advert for the lower band pass. I am also interested in your comment that you weren’t sure if you had made the right choice and just wonder how much of a difference do those 2nm really make? Barry & Steve are using 5nm Astrodons in their Spanish setup with great results, but would 3nm be even better?? If you were about to purchase the Astrodon Ha filter now, which would you order?

Sorry to take the thread off on a slight tangent, but hopefully it is generally useful and vaguely relevant!

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steppenwolf

steppenwolf

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1 hour ago, PhotoGav said:

If you were about to purchase the Astrodon Ha filter now, which would you order?

Let's answer that one first! I'd buy the 3nm version again without hesitation.

I only wonder about the 5nm from time to time as I note that a lot of imagers have taken the general advice (normally from Ian King whose opinion I would normally rely on) of buying the 5nm Ha but the 3nm OIII so that is cause for self doubt! However, I have never been one for taking the 'safe option' so decided to go for broke. This image is further confirmation that for me, the 3nm choice was right. The fact that NII is missing from the image doesn't worry me as I am deliberately aiming for Ha but there is the possibility that I might be missing some nuances in my images by its absence even if it is not an emission that I am aiming for. At the end of the day, I am after a detailed but attractive image rather than a scientifically accurate rendition so that NII *might* help achieve that goal but I'm happy with the results that I am achieving without it.

Barry and Steve do indeed get great results from their new observatory but it is impossible for me say if they would get better or different results from the use of 3nm Ha filtering instead of 5nm although with their much better skies and greater imaging opportunities they would be in a good position to compare the results of the two!

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PhotoGav

PhotoGav

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Thank you Steve, an interesting answer. Like so much of this astrophotography, there are many possible solutions all with their own advantages and the only way to choose your favourite is through experimentation and looking at other people's results. Though even that is generally comparing apples and oranges!

I look forward to your next instalment of The Rosette Nebula. 

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steppenwolf

steppenwolf

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21 minutes ago, toxic said:

if you did add the NII to the image would you be keeping it mono or colour

The NII would be in the red portion of the light spectrum right next door to the Ha signal so it would potentially contribute to both an 'Ha' mono and a Hubble palette image. I think that it would most likely affect a mono image the most.

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AndyUK

AndyUK

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Another stunning image, Steve :).  I'd be ecstatic to get anything close to this quality (but FWIW, I too reckon a slight shift in framing would make it even better...).

On the subject of 3nm vs 5nm Ha, there's an interesting comparison on this page.

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