APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

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APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

Post by APOD Robot » Mon Oct 15, 2018 4:08 am

Image M16: In and Around the Eagle Nebula

Explanation: From afar, the whole thing looks like an Eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed. In this cavity tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and dust. The Eagle emission nebula, tagged M16, lies about 6500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of the Serpent (Serpens). This picture involved over 25 hours of imaging and combines three specific emitted colors emitted by sulfur (colored as red), hydrogen (yellow), and oxygen (blue).

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BDanielMayfield
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Re: APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

Post by BDanielMayfield » Mon Oct 15, 2018 4:39 am

APOD Robot wrote:
Mon Oct 15, 2018 4:08 am
Explanation: This picture[/url] involved over 25 hours of imaging and combines three specific emitted colors emitted by sulfur (colored as red), hydrogen (yellow), and oxygen (blue).
The colors look unusual and somewhat strange. Isn't it more common to map hydrogen to red, sulfur to yellow and oxygen to green? I'd love to see a comparison image done with the more typical colors.
"Happy are the peaceable ... "

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Re: APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

Post by Guest » Mon Oct 15, 2018 5:18 am

Why do the pictures suddenly load so slowly

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Ann
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Re: APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

Post by Ann » Mon Oct 15, 2018 6:40 am

BDanielMayfield wrote:
Mon Oct 15, 2018 4:39 am
APOD Robot wrote:
Mon Oct 15, 2018 4:08 am
Explanation: This picture[/url] involved over 25 hours of imaging and combines three specific emitted colors emitted by sulfur (colored as red), hydrogen (yellow), and oxygen (blue).
The colors look unusual and somewhat strange. Isn't it more common to map hydrogen to red, sulfur to yellow and oxygen to green? I'd love to see a comparison image done with the more typical colors.
I don't think the colors are untypical, as such, but the processing just may be a bit unusual. Here is another narrowband picture of the Eagle Nebula, this time by Jason Guenzel. Here is a green-looking one, whose photographer I don't know, sorry. Here is a red and blue one by Marcel Drechler.

Don't tell anyone, but the colors of today's APOD clash so strongly with my sense of aesthetics that I can hardly look at it.

Ann
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Re: APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

Post by Boomer12k » Mon Oct 15, 2018 7:34 am

And here is my amateur shot... close up with my 10" Meade LX-200...and DSI-II color camera... back in 2011... I probably reprocessed it in 2014...

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BDanielMayfield
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Re: APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

Post by BDanielMayfield » Mon Oct 15, 2018 10:22 am

My apologies to the astrophotographer, Andrew Klinger, for the disparaging tone of my (and today's) first post about this excellent APOD. Here is what he wrote about the filters used and the color processing:
Here is my completed image of the Eagle Nebula (M16) imaged with Sulphur, Hydrogen, and Oxygen narrowband filters. This false-color widefield image of the nebula represents the strong oxygen signal as cyan, hydrogen as yellow/orange, and the stronger sulphur signal as red. Naturally, this nebula is nearly all red in color, as hydrogen-alpha dominates the field. With selective filters and processing I have stretched the intensity of the Oiii and Sii to better represent where they lie in the nebula.
Among his peers (his fellow astrophotographers) there is nothing but well deserved praise for this work. Sorry Andrew.

Bruce
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Re: APOD: M16: In and Around the Eagle Nebula (2018 Oct 15)

Post by Chris Peterson » Mon Oct 15, 2018 1:51 pm

BDanielMayfield wrote:
Mon Oct 15, 2018 10:22 am
My apologies to the astrophotographer, Andrew Klinger, for the disparaging tone of my (and today's) first post about this excellent APOD. Here is what he wrote about the filters used and the color processing:
Here is my completed image of the Eagle Nebula (M16) imaged with Sulphur, Hydrogen, and Oxygen narrowband filters. This false-color widefield image of the nebula represents the strong oxygen signal as cyan, hydrogen as yellow/orange, and the stronger sulphur signal as red. Naturally, this nebula is nearly all red in color, as hydrogen-alpha dominates the field. With selective filters and processing I have stretched the intensity of the Oiii and Sii to better represent where they lie in the nebula.
Among his peers (his fellow astrophotographers) there is nothing but well deserved praise for this work. Sorry Andrew.
There is a real problem with this kind of mapping, however. When each filter is assigned to a single output channel, we can separate them. Indeed, I often do this with interesting APOD images- look at the red, green, and blue channels separately to get a better idea of where the oxygen or hydrogen are. You can't always see that directly in the false color image because of the way the elements (and therefore the colors) mix. With a mapping like this, the different filter channels are mixed into pairs of output channels, which means the data is mixed in a way that prevents elements from being isolated. It can certainly make for an aesthetically pleasing image, but it is of much less scientific value.
Chris

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