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#1 the Elf

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Posted 17 January 2020 - 01:27 PM

Dear all,

 

surprisingly the sky was clear and quite transparent last night so I was able to capture 3h 45min Ha of the Jellyfish. I need to take more but as it is now raining again I took the time to process the data that I have. It is Ha only but for the fun of it I colorized it, the nebula in red and a touch of blue to the stars:

 

Jellyfish_Colorized_low.jpg

 

15x15min, Baader 7nm Ha, T3i mono mod, TS 65/420 quad.

 

Can anyone tell how much O-III is in this object? I tend to try a HOO.

 

clear skies!

the Elf


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#2 Madratter

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Posted 17 January 2020 - 02:02 PM

Nice. :)

 

I'm not sure of the object as a whole, but the Jellyfish itself has much stronger SII than OIII. That surprised me, but is the case. There is some OIII but it is fairly faint compared to the Ha and the SII.



#3 Stelios

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Posted 17 January 2020 - 03:15 PM

Really? I have the opposite result, unless I mixed my filters. Strong Oiii, very weak Sii. 


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#4 Madratter

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Posted 17 January 2020 - 03:24 PM



Really? I have the opposite result, unless I mixed my filters. Strong Oiii, very weak Sii. 


I could be wrong, but see when I look at Astrobin with SHO images of it, that seems to be what others get as well. See this for example:

 

get.jpg?insecure


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#5 sunnyday

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Posted 17 January 2020 - 03:28 PM

spock always said fascinating, so your photo is fascinating.



#6 Stelios

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Posted 17 January 2020 - 07:54 PM

I could be wrong, but see when I look at Astrobin with SHO images of it, that seems to be what others get as well. See this for example:

 

get.jpg?insecure

Most "SHO" is so strongly manipulated that it's hard to tell what it started as. 

As I said, unless I had my filters reversed, Oiii is much stronger. 

When I have some time I'll check other images taken with these filters (I shot Jellyfish in 2018) as it *is* possible to mismark the filters in SGP. 



#7 Madratter

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Posted 17 January 2020 - 08:43 PM

Well, like you said, it is always possible something got mixed up. But this is why I believe what I said. And it does seem to match what I see in other images about where the OIII is showing up.

 

First the SII

JellySIIMaster.JPG

 

And then the OIII

 

JellyOIIIMaster.JPG

 

 


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#8 richorn

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Posted 18 January 2020 - 12:11 AM

I'm shooting the Jellyfish right now, and just got my first 2 frames of OIII.  They look exactly like @Madratter's image above.  

 

SII, however is quite similar in strength to the Ha.

 

 

Screenshot-2020-01-17-21.13.05.jpg


Edited by richorn, 18 January 2020 - 12:17 AM.

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#9 the Elf

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Posted 18 January 2020 - 03:17 PM

Thanks for the feedback! Can anyone tell how the S-II signal compares to Ha? Same level? With my uncooled DSLR this object is near my limit for Ha. I am thinking about an S-II filter but until now I was assuming S-II is always way weaker so out of reach for me. Are there more objects with strong S-II? I would not want to buy a filter for just one object.

 

@Stelios: if the example images are true SHO (so no stars replaced by RGB stars) and if the stars appear near white a tendency may be visible. Of course the low lights may be stretched a lot. In this case the dim stars must have a yellow color. Looking at Madratter's image I see the typical cocoon like shape of O-III, very similar to the crescent nebula where O-III looks like an envelope to the structure. I guess you mixed your filters indeed.


Edited by the Elf, 18 January 2020 - 03:24 PM.


#10 Madratter

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Posted 18 January 2020 - 03:54 PM

The SII level is not as strong as the Ha, but I think it is the strongest I can recall seeing in an object (comparing Ha to SII).



#11 Becomart

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Posted 18 January 2020 - 04:00 PM

How do you artificially add the colour? I’ve never tried it. I tend to capture 5-10hrs per channel and usually end up waiting the following year to grab the other channels. I’m impatiently waiting to process the crescent Nebula, ngc 410 and ngc 896. 



#12 the Elf

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Posted 19 January 2020 - 06:59 AM

The color was added in PI. Pixel Math to convert the 1 channel mono to a 3 channel RGB (I guess there is a better way to do it). Next took the original 1 channel Ha to MultiscaleMedianTransform and deactiveted the smallest 5 layers (depends on imaging scale and star diameter). Stretched the mask and removed a few bright stars using clone stamp. With the mask on the RGB image added red and saturation using curves. With the mask inverted a bit blue to the stars also with curves. Quite simple.

Here is another example using the same technique:

http://www.elf-of-lo...j_Veil2018.html

If was only a test, checking if the RC's reducer works with the quad. The full res gives the answer.....



#13 jerahian

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Posted 19 January 2020 - 07:41 AM

Are there more objects with strong S-II? I would not want to buy a filter for just one object.

I know the flaming star nebula has much stronger SII vs. OIII as well.  Working on that now myself.


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