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M20 The Trifid Nebula taken with Narrow band filters.
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Jul 17, 2021 00:52:14   #
Ballard Loc: Grass Valley, California
 
I have recently started to play with Narrow band imaging to see what it can show. In my latest attempt I imaged M20 (Messier object 20 the Trifid nebula) in Sagittarius. For this image I used 3 different 5 nanometer narrow band filters (Hydrogen Alpha (Ha), Oxygen 3 (OIII) and Sulfur 2 (SII) filters), to take 3 sets of images (one each filter).
The images where taken with an 11 megapixel Cooled CCD camera connected 16 inch Schmidt Cassegrain telescope at F10 (~4000mm focal length). Each set contained 16 images and each image was a 15 minute exposure for a total exposure time of 12 hours across the 3 sets. Each individual set was stacked together to improve the single to noise of each filter used. I also used Dark frames, Flat frames (different for each filter) and bias frames. To combine stacked images from each filter type into a full color image I used what is known as the Hubble Palette where SII is assigned to the red channel, Ha to the green channel and OIII to the blue channel. This creates a "False Color image", however the channels are picked this way to make it easier to see the composition of the nebula. On initial combination the nebula was very green and I had to greatly reduce the green to see the other colors come out, which is expected since the nebula is mainly hydrogen gas that was assigned to the green channel. The colors show some of the chemical composition of the nebula, the yellow through red show the ionized sulfur, the aqua through blue shows the ionized oxygen. Although I greatly reduce the green, the hydrogen signature still comes through as the orange to yellow color coming from the combination of the red from the sulfur mixed with the green from the hydrogen. Likewise the the aqua color being a combination of green and blue with the blue from the ionized oxygen and the green from the hydrogen. (Note: I'm using the color names in a loose fashion here as they are a bit arbitrary since the color assignment is not the real colors emitted by the elements in the nebula but only used to make easy to see the different components of the nebula). The first image is of the full nebula taken at a 4000mm focal length. The second image is a cropped version of the first image centered on what has been called the unicorn nebula inside the Trifid nebula. The second version has also been contrast enhanced to try and bring out more detail. For those interested last year I posted an image of the Trifid nebula taken with a DSLR at
https://www.uglyhedgehog.com/t-652657-1.html
The image taken with a DSLR is what the nebula would look like to our eyes if they where sensitive enough.

All questions comments and suggestions are welcome.

The Trifid nebula using narrow band filters to create a False Color image using the Hubble Palette.
The Trifid nebula using narrow band filters to cre...
(Download)

Zoomed in section of the nebula (if you squint just right you can see the head of the unicorn).
Zoomed in section of the nebula (if you squint jus...
(Download)

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Jul 17, 2021 03:19:45   #
angler Loc: StHelens England
 
Excellent.

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Jul 17, 2021 06:11:22   #
Julian Loc: Sarasota, FL
 
I am so involved in studying about the vastness of the Universe that this amazing image just hits home. Beautifully done with incredible technique! Thank you for posting.

Reply
 
 
Jul 17, 2021 06:29:03   #
nimbushopper Loc: Tampa, FL
 
Well done!

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Jul 17, 2021 06:42:34   #
Irvingite Charles Loc: Irving, Tx
 

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Jul 17, 2021 07:36:40   #
dpullum Loc: Tampa Florida
 
It is interesting that "Narrow Band Filters" are applied to close and far imaging. Close is in Colonoscopy and far is Astronomy. One of my early jobs as a Chemist was using an emission spectrograph to determine the elements contained in ashed biological lung samples each element having one or more peak narrow color emissions when heated with a carbon arc. The simple one we experience as children is the prism making a rainbow splitting the colors.

For the UHH people like me, innocent in Narrow Band Photography, here is a discussion of Narrow Band as applied to astrophysics...
https://astrobackyard.com/narrowband-imaging/
When you get bored with astronomy here is the universe of colorectal polyp detection.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474109/

Here is a discussion of the equipment used... I am pondering how I may attach it to my Pocket Super-Zoom camera.
https://astrobackyard.com/starlight-xpress-ccd-camera/

I will admit that this subject in detail is a bit much for me to ponder having only a half cup of coffee. But am I on a tangent when looking at less than $600 attached with USB to a computer analyzing the light from a telescope? This price is reasonable considering that in 1888 the Kodak box camera was introduced at $25 about $600 in today's dollars.
https://www.highpointscientific.com/starlight-xpress-lodestar-pro-monochrome-autoguider-blue-110-0019
https://notquiteinfocus.com/2014/04/23/a-brief-history-of-photography-part-6-kodak-the-birth-of-film/

I found that there are screw-on filters that provide separation:
https://astrobackyard.com/narrowband-color-camera/

Thank you, Ballard, You, have opened a whole new world, correction ... Universe... to us. The gallery here is interesting:
https://redstickastro.com/

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Jul 17, 2021 09:03:48   #
Longshadow Loc: Audubon, PA, United States
 

Reply
 
 
Jul 17, 2021 13:44:49   #
Ballard Loc: Grass Valley, California
 
angler wrote:
Excellent.


Hi angler
Thanks for checking out the narrow band image of the Trifid nebula and for the comment.

Reply
Jul 17, 2021 13:48:47   #
Ballard Loc: Grass Valley, California
 
Julian wrote:
I am so involved in studying about the vastness of the Universe that this amazing image just hits home. Beautifully done with incredible technique! Thank you for posting.


Hi Julian
Thanks for viewing my latest try at astrophotography and for the comment. I also enjoy learning about the universe in which we live.

Reply
Jul 17, 2021 13:49:47   #
Ballard Loc: Grass Valley, California
 
nimbushopper wrote:
Well done!


Hi nimbushopper
Thanks for viewing the narrow band image of M20 and for the comment.

Reply
Jul 17, 2021 13:51:13   #
Ballard Loc: Grass Valley, California
 
Irvingite Charles wrote:


Hi Irvingite Charles
Thanks for checking out my narrow band image of the Trifid nebula and for the Thumbs up.

Reply
 
 
Jul 17, 2021 14:02:52   #
Ballard Loc: Grass Valley, California
 
dpullum wrote:
It is interesting that "Narrow Band Filters" are applied to close and far imaging. Close is in Colonoscopy and far is Astronomy. One of my early jobs as a Chemist was using an emission spectrograph to determine the elements contained in ashed biological lung samples each element having one or more peak narrow color emissions when heated with a carbon arc. The simple one we experience as children is the prism making a rainbow splitting the colors.

For the UHH people like me, innocent in Narrow Band Photography, here is a discussion of Narrow Band as applied to astrophysics...
https://astrobackyard.com/narrowband-imaging/
When you get bored with astronomy here is the universe of colorectal polyp detection.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474109/

Here is a discussion of the equipment used... I am pondering how I may attach it to my Pocket Super-Zoom camera.
https://astrobackyard.com/starlight-xpress-ccd-camera/

I will admit that this subject in detail is a bit much for me to ponder having only a half cup of coffee. But am I on a tangent when looking at less than $600 attached with USB to a computer analyzing the light from a telescope? This price is reasonable considering that in 1888 the Kodak box camera was introduced at $25 about $600 in today's dollars.
https://www.highpointscientific.com/starlight-xpress-lodestar-pro-monochrome-autoguider-blue-110-0019
https://notquiteinfocus.com/2014/04/23/a-brief-history-of-photography-part-6-kodak-the-birth-of-film/

I found that there are screw-on filters that provide separation:
https://astrobackyard.com/narrowband-color-camera/

Thank you, Ballard, You, have opened a whole new world, correction ... Universe... to us. The gallery here is interesting:
https://redstickastro.com/
It is interesting that "Narrow Band Filters&q... (show quote)


Hi dpullum
Thanks for viewing my newest image of the Trifid nebula using narrow band filters and for the all the info links and the comment. There narrow band filters I use don't completely eliminate light from other elements and molecules as they are 5 nanometers wide but do tend to indicate the predominance of the those elements they are targeted for. To get details would require a real spectroscope to see all the individual lines, these devices are available to the armature market, of course they don't produce an image of the object only the spectra which can be used to get a much better idea of the elements available. The narrow band filter like I am using can show structure details in the object that might otherwise be hard to see.

Reply
Jul 17, 2021 14:04:01   #
Ballard Loc: Grass Valley, California
 
Longshadow wrote:


Hi Longshadow
Thanks for the Thumbs up and for checking out the image of the Trifid nebula.

Reply
Jul 18, 2021 05:38:40   #
J-SPEIGHT Loc: Akron, Ohio
 
Ballard wrote:
I have recently started to play with Narrow band imaging to see what it can show. In my latest attempt I imaged M20 (Messier object 20 the Trifid nebula) in Sagittarius. For this image I used 3 different 5 nanometer narrow band filters (Hydrogen Alpha (Ha), Oxygen 3 (OIII) and Sulfur 2 (SII) filters), to take 3 sets of images (one each filter).
The images where taken with an 11 megapixel Cooled CCD camera connected 16 inch Schmidt Cassegrain telescope at F10 (~4000mm focal length). Each set contained 16 images and each image was a 15 minute exposure for a total exposure time of 12 hours across the 3 sets. Each individual set was stacked together to improve the single to noise of each filter used. I also used Dark frames, Flat frames (different for each filter) and bias frames. To combine stacked images from each filter type into a full color image I used what is known as the Hubble Palette where SII is assigned to the red channel, Ha to the green channel and OIII to the blue channel. This creates a "False Color image", however the channels are picked this way to make it easier to see the composition of the nebula. On initial combination the nebula was very green and I had to greatly reduce the green to see the other colors come out, which is expected since the nebula is mainly hydrogen gas that was assigned to the green channel. The colors show some of the chemical composition of the nebula, the yellow through red show the ionized sulfur, the aqua through blue shows the ionized oxygen. Although I greatly reduce the green, the hydrogen signature still comes through as the orange to yellow color coming from the combination of the red from the sulfur mixed with the green from the hydrogen. Likewise the the aqua color being a combination of green and blue with the blue from the ionized oxygen and the green from the hydrogen. (Note: I'm using the color names in a loose fashion here as they are a bit arbitrary since the color assignment is not the real colors emitted by the elements in the nebula but only used to make easy to see the different components of the nebula). The first image is of the full nebula taken at a 4000mm focal length. The second image is a cropped version of the first image centered on what has been called the unicorn nebula inside the Trifid nebula. The second version has also been contrast enhanced to try and bring out more detail. For those interested last year I posted an image of the Trifid nebula taken with a DSLR at
https://www.uglyhedgehog.com/t-652657-1.html
The image taken with a DSLR is what the nebula would look like to our eyes if they where sensitive enough.

All questions comments and suggestions are welcome.
I have recently started to play with Narrow band i... (show quote)

Outstanding images

Reply
Jul 18, 2021 06:59:37   #
malawibob Loc: South Carolina
 
Fantastic photo. I am curious as to how the picture has no movement on the stars with a 15 minute exposure.

Reply
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