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Archive 2015 · The Day of the Trifid

  
 
StarNut
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p.1 #1 · p.1 #1 · The Day of the Trifid


The Trifid Nebula (cataloged as Messier 20) is so called because it appears to have three lobes in the reddish part. This is a star-forming region, which includes an emission nebula (the reddish part), reflection nebula (blue part) and dark nebulae (the dark parts that appear to divide the emission nebula). The Trifid Nebula is approximately 5,200 light years from us, about 40 light years across, and glows brightly at an apparent magnitude of 6.3 (meaning possibly visible to the naked eye in the very darkest skies).

I previously photographed this with my small scope, as part of a much larger field (the photo of Trifid Nebula and Lagoon Nebula, posted here a couple of years ago.

I'm quite partial to it, for the coincidence of its name sort of being shared with one of my favorite post-apocalyptic books, John Wyndham's "The Day of the Triffids," from 1951.

It took me four months to gather the data of this photo (there is over 30 hours of light-frame exposures in this photo, and many times that much that I tossed as unusable); the weather in South Australia has been dismal for the last several months.

Telescope: RC Optical Systems 14.5" carbon-truss Ritchey-Chretien Cassegrain with ion-milled optics
Camera: Santa Barbara Instruments Group STL11000M
Mount: Software Bisque Paramount ME

Enjoy!

http://www.de-regt.com/Astronomy/M20.40.jpg



Jul 28, 2015 at 10:27 AM
JimFox
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p.1 #2 · p.1 #2 · The Day of the Trifid


That is super cool. The look of this one is amazing!

Jim



Jul 28, 2015 at 01:02 PM
sachman
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p.1 #3 · p.1 #3 · The Day of the Trifid


Wow just awesome! Love the clarity and really nice colour balance!


Jul 28, 2015 at 06:56 PM
Sunny Sra
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p.1 #4 · p.1 #4 · The Day of the Trifid


Looks like a rose. beautiful work as always


Jul 28, 2015 at 07:41 PM
dgdg
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p.1 #5 · p.1 #5 · The Day of the Trifid


I like the detail in the dust lanes and all the star colors.

David



Jul 28, 2015 at 08:29 PM
cams884
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p.1 #6 · p.1 #6 · The Day of the Trifid


Amazing


Jul 29, 2015 at 02:18 AM
ramdisk
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p.1 #7 · p.1 #7 · The Day of the Trifid


Wow


Jul 29, 2015 at 04:22 AM
harshaj1
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p.1 #8 · p.1 #8 · The Day of the Trifid


Magnificent
Harsha



Jul 29, 2015 at 06:10 AM
Frogfish
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p.1 #9 · p.1 #9 · The Day of the Trifid


Spectacular ! Thanks for the educational introduction too.


Jul 29, 2015 at 07:53 AM
StarNut
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p.1 #10 · p.1 #10 · The Day of the Trifid


Thanks for all the kind words!


Jul 29, 2015 at 08:06 PM
Jim Bau
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p.1 #11 · p.1 #11 · The Day of the Trifid


Your shots are always amazing, and this one leads the pack! Thank you for sharing the fruits of your many, many hours of hard work with us!


Jul 29, 2015 at 10:00 PM
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p.1 #12 · p.1 #12 · The Day of the Trifid


Beautiful! Thanks for posting. Also, small world... I used to work for RC Optical Systems and it's nice to see one of their 'scopes being used by someone of your skill to put together this image.


Jul 29, 2015 at 11:32 PM
wnichols
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p.1 #13 · p.1 #13 · The Day of the Trifid


Wow, this is truly amazing. Thanks for sharing the fruit of your many hours of hard work.


Jul 30, 2015 at 06:16 AM
sinizter
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p.1 #14 · p.1 #14 · The Day of the Trifid


Really amazing.

I would love to know the workflow on how to achieve something like this....



Jul 30, 2015 at 08:17 AM
StarNut
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p.1 #15 · p.1 #15 · The Day of the Trifid


Thanks again!

sinizter wrote:
Really amazing.

I would love to know the workflow on how to achieve something like this....


I'll give it a try. Each image is different, of course, in subtle ways, but all have lots of similarities.

1. Acquire light-frame images (photos of the target). In ideal conditions, this take only a few nights (even for me, an exposure freak). This was a horrible stretch of weather and general imaging conditions, so I acquired data over four months. Ick! This involves more than just pointing the camera/scope at the object being imaged, since it's imperative to keep it precisely pointed at the same place (within a small fraction of a pixel). To do this, we "guide," using the software to glom onto a star (using a separate chip in the camera--or a separate camera/guidescope piggybacking on the main scope; for this image, I used a second, internal chip in the camera); this is not always possible, even with the best equipment, since wind and/or squirrelly skies will defeat all efforts. I want to take many, many exposures, each of significant duration, so that I can toss the bad ones and still have lots to work with, and because you have to have a lot of individual subexposures in order to use statistical methods to combine them in a way that effectively reduces noise. All images taken through the Ha and OIII filters were 30 minutes in duration, and all taken through the luminance, red, green and blue filters were 15 minutes long.

2. Along the way, you take flat-frame images. These are images that allow you to correct for flaws in the optical train, including mild vignetting and dust (particularly dust on the glass covering the imaging chip). This is done at dawn (you get an even, flat light then), and you want to get many for each filter (and for each side of the meridian, since the camera rotates 180 degrees.

3. You also acquire (and constantly update) a library of dark frames. These super-sensitive chips have "dark current" running through them, which causes thousands of little white spots (of varying intensity) to appear on the chip over time; this dark current is repeatable (not including the inevitable noise), so we take a lot of individual exposures with the shutter closed, at night, combine them to reduce the noise, and then subtract them from the individual light frames to largely eliminate the effects of the dark current. Dark current isn't noise, but it's unwanted signal.

4. Acquisition of the light, dark and flat frames is done automatically; before I go to bed at night (I live in Seattle, USA, and my equipment is in the South Australia desert), I tell the software what I want to do that night, and it will do it (weather permitting, of course). When I've acquired enough data, it's time to process the data. This processing takes many hours.

5. The first steps are the so-called "pre-processing": Using master flats and master darks to get clean subexposures, then combining the subexposures to reduce noise, creating masters for each filter (this image had images taken through six filters; it took several hours to get this tedious process done, since I have many dozens of subexposures, and each of the six sets of filtered data has to be pre-processed separately).

6. Then comes the fun part. For this image, I wanted to use the narrow-band data (Oxygen III, which passes light emitted only by doubly-ionized oxygen atoms, and Hydrogen Alpha, which passed light emitted only by ionized hydrogen atoms), mixing it in with the luminance layer, and all three primary color channels This enhances the detail in the luminance layer, and helps get the color data to show up when the luminance layer is applied..

7. Once I've created the hybrid masters, I combine the new red, green and blue channels into an RGB color image, Then I spend a lot of time carefully stretching the histogram (the raw master frames will show only a few stars; the nebula is so much dimmer that a 16-bit linear image typically won't show any of the nebula). Then I spend some time getting rid of light gradients, correcting the color balance, filtering out remaining noise and faulty pixels, and other things, increasing the saturation.

8. Once I'm satisfied that I'm reasonably close with the RGB layer, I do the same sort of things to the luminance layer (other than saturation, of course, since this is a gray-scale image). We use "luminance layering" for most of our images; the RGB layer carries the color data, and the luminance layer gives the final image its detail, much like analog color TV worked.

9. Then I layer the luminance layer on the color layer, and I have the first version of the real image. I spent some significant time working with this image, sharpening the luminance layer, working on getting the color to come through correctly, fixing subtle flaws that I hadn't seen before, etc.

It's a labor of love, but it gives me a tremendous thrill to end up with such a pretty picture of something that looks like a fuzzy blob when looking at it through the scope with my eyepieces.

I hope this helps! This is not for the faint-of-heart!

Mark



Jul 30, 2015 at 10:27 AM
dgdg
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p.1 #16 · p.1 #16 · The Day of the Trifid


sinizter wrote:
Really amazing.

I would love to know the workflow on how to achieve something like this....


Definitely amazing captures and processing Mark.
You forgot to mention the cash outlay.

Adam Block has an amazing video series on how to process great images like Mark's. The videos are very well done. The techniques are incredibly cogent. I would consider them a must read for any beginning astro imager. I used some of his videos to help me with a deliberate approach to processing the milky way. Regardless of your astro 'style' you can use Adam's techniques to objectively create the look and feel you want. I don't have any financial relationship with his video series. They are just that good.

https://www.adamblockphotos.com/store/p7/Powerful_Processing_in_Photoshop.html

David




Jul 30, 2015 at 10:39 AM
sinizter
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p.1 #17 · p.1 #17 · The Day of the Trifid


dgdg wrote:
Definitely amazing captures and processing Mark.
You forgot to mention the cash outlay.

Adam Block has an amazing video series on how to process great images like Mark's. The videos are very well done. The techniques are incredibly cogent. I would consider them a must read for any beginning astro imager. I used some of his videos to help me with a deliberate approach to processing the milky way. Regardless of your astro 'style' you can use Adam's techniques to objectively create the look and feel you want. I don't have any financial relationship with his video series. They are just
...Show more

Thanks for the link. I'll have a read when I get some spare time.

StarNut wrote:
Thanks again!

I'll give it a try. Each image is different, of course, in subtle ways, but all have lots of similarities.



Thanks for that. Interesting reading.




Jul 30, 2015 at 10:50 AM
Cheryle Sytsma
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p.1 #18 · p.1 #18 · The Day of the Trifid


Quite well captured... amazing!


Jul 30, 2015 at 02:58 PM
StarNut
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p.1 #19 · p.1 #19 · The Day of the Trifid


dgdg wrote:
Definitely amazing captures and processing Mark.
You forgot to mention the cash outlay.

Adam Block has an amazing video series on how to process great images like Mark's.


Yeah, the expense isn't for the faint-of-heart, either. Like with conventional photography, however, you do get what you pay for. I just love this equipment! I dreamed of having equipment this nice for years, and then decided that I need to give it a try. Tasting the forbidden fruit and all that....

Adam Block is a true guru at this, and a very pleasant guy, also. I have heard that he's a wonderful host at his program in Arizona, too.



Jul 30, 2015 at 11:49 PM
Mark Metternich
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p.1 #20 · p.1 #20 · The Day of the Trifid


Dang!



Jul 31, 2015 at 03:21 PM





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