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gorann

Lobster Claw Nebula - My first attempt on HaOiii

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The moon is up although not terribly bright any more. Still, it made me go for NB and for the first time use my Baader 8.5 nm Oiii filter that I bought years ago. I aimed at the Lobster Claw nebula in Cassiopeia. Grabbed 10 x 15 min of Oiii before the midnight meridean flip and 18 x 15 min Ha (Baader 3.5 nm filter) until the morning. I made a synthetic green by mixing Ha and Oiii 50:50. Then I tweeked the colours towards an RGB like palette. Registered and calibrated in PI and processed in PS.

So far I have only used my equipment for RGB and Ha so this is the first time I process my own pure NB data (I have had a few goes at processing public NB data). A reason for this is that I got a nice dark sky so RGB is always more tempting. SQM was 21.1 yesterday even with the moon up.

Equipment used: Esprit 150 + 0.79x 3" TS reducer + ASI1600MMpro. Guiding with ST80 and QHY5L-IIM.

Any comments most appreciated. I am for example a bit unsure how much of the Ha in the surrounding sky I should let through. My first versions were quite reddish all over and I finally decided to tweak the curves to put more emphasis on the brighter parts of the image to make the claws stand out.

 

 

20190921 Sh2-157 PS17smallSign.jpg

Edited by gorann
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Brilliant, your colour mixing is really inspiring. Do you find the longer exposures with the ZWO1600 more effective? I@ve never gone longer than 10 mins, can I ask what gain? Thanks

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Just now, AbsolutelyN said:

Brilliant, your colour mixing is really inspiring. Do you find the longer exposures with the ZWO1600 more effective? I@ve never gone longer than 10 mins, can I ask what gain? Thanks

Thanks!

I also started off doing 3, 5 or 10 min with this camera but for NB I think 15 min is often better, depending  upon how bright the stars are and how faint the nebulosity is. For this one I think 15 min was about right. I always use gain 139 (unity) and offset 50, -20°, I read somewhere that it was a good start and I have remained there. But maybe 10 min and gain 200 would be equally good. Maybe that is one of the remaining advantages with CCD - you do not have to worry about gain and offset😉

I have been tweeking coulours and contrast a bit so here is my current version:

20190921 Sh2-157 PS24smallSign.jpg

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Started off from scratch today to make a new version where I brought up more data from the darker regions and also brought up some more of the blue signal. Added it with layer masks onto the old version. Getting there.....

 

20190921 Sh2-157 PS32smallSign.jpg

Edited by gorann
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Number 1 or 2 for me....a smoldering image....very nice.  I just cant get bicolor to work. (except for teh obvious ones..veil...crescent...etc).  Love this image.  NGC 7358 is just off the right hand edge.  You got the little star cluster though that forms the eye (or antenna) of the lobster (hes upside down.....boiled and ready to consume).

Rodd

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Great image though a bit over coloured for my taste, can't find it in CduC .

alan

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5 hours ago, Rodd said:

Number 1 or 2 for me....a smoldering image....very nice.  I just cant get bicolor to work. (except for teh obvious ones..veil...crescent...etc).  Love this image.  NGC 7358 is just off the right hand edge.  You got the little star cluster though that forms the eye (or antenna) of the lobster (hes upside down.....boiled and ready to consume).

Rodd

Thanks Rodd!

yes there is a lot in this area, and the Bubble Nebula is not far off. A mosaik one day is a possibility.

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8 hours ago, Laurin Dave said:

Lovely, looks well cooked to me 😉

Thanks Dave!

 

8 hours ago, alan potts said:

Great image though a bit over coloured for my taste, can't find it in CduC .

alan

Thanks Alan and you have a point there and I may agree, and maybe Dave tried to hint about the same thing.

So here is a slightly less cooked lobster claw (just reduced the red saturation a bit)

Cheers

Göran

 

20190921 Sh2-157 PS34smallSign.jpg

Edited by gorann
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I like the way the yellow/orange is coming through in this, not something I have seen in any of my Canon images but I guess this is the broadband filters showing through, I don't have any of those. At least I found where this is though C du C doesn't list it, at least not on mine. It's a cracking image and looks like its title Goran, lovely work.

Alan

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1 hour ago, alan potts said:

I like the way the yellow/orange is coming through in this, not something I have seen in any of my Canon images but I guess this is the broadband filters showing through, I don't have any of those. At least I found where this is though C du C doesn't list it, at least not on mine. It's a cracking image and looks like its title Goran, lovely work.

Alan

Thanks Alan. Yes I am usually also an RGB person, or HaRGB or LumRGB, so this was an new thing for me. For my Canons I invested in the relatively cheap Astronomik 12nm Ha clip-on filter so I could do some Ha when the moon was up. Worked surprisingly well.

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34 minutes ago, MartinFransson said:

Very nice! I like that last edit the best.

Tack Martin!

Yes, I am happy for the input here setting me strait about the colour - reducing the red saturation made it better.

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1 hour ago, alan potts said:

I like the way the yellow/orange is coming through in this, not something I have seen in any of my Canon images but I guess this is the broadband filters showing through, I don't have any of those. At least I found where this is though C du C doesn't list it, at least not on mine. It's a cracking image and looks like its title Goran, lovely work.

Alan

Regarding the celestial localization of my images, you could go to my Astrobin page (see my signature below) and there it has been plate solved and mapped onto the sky. Astrobin does that automatically when we upload our images there so whenever you see images there you can usually also see where they are in the sky.

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14 hours ago, alan potts said:

I like the way the yellow/orange is coming through in this, not something I have seen in any of my Canon images but I guess this is the broadband filters showing through, I don't have any of those. At least I found where this is though C du C doesn't list it, at least not on mine. It's a cracking image and looks like its title Goran, lovely work.

Alan

I had the similar issue on Stellarium.  It can be found if you enable the SH catalogue and look for SH 2-157. 

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2 hours ago, wornish said:

I had the similar issue on Stellarium.  It can be found if you enable the SH catalogue and look for SH 2-157. 

With my track record of dealing with any form of IT I am likely to re-direct air traffic, I will have a look.

Alan

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    • By gorann
      While waiting for clear skies (may happen Wednesday here, maybe) I have entertained myself with reprocessing data from the autumn. This is Ha (10 x 15 min) and Oiii (18 x 15 min) from my Esprit 150 with 0.79 x TS 3" reducer and ASI1600MM (gain 139, offset 50. -20°C). So totally 7 hours. I initially put Ha to red, Oiii to blue, and made a 50:50 mix of Ha and Oiii for the green channel. Then I tweaked the colours in PS towards an "RGB look". I endeavoured into doing a bit of HDRM and deconvolution in PI before I escaped back into my relative comfort zone, which is PS. Finally, I boosted the dust a bit by adding a few % of an Equalize layer in PS (a method suggested by Olly @ollypenricehere). I think the image shows a rather unusual amount of detail and I hope I have not over cooked it. Or have I?

      Cheers, Göran

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