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gnomus

Flying Bat and Squid Nebulae in Cepheus

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The squid is an extremely faint object! I should have realised this when I noticed that individual subs showed no hint of it whatsoever.  And despite over 10 hours of OIII, it proved extremely difficult to extract any reasonable information from the data without there being an eruption of noise.  The decision then is to what extent this faint object should be 'revealed' in the final image.  Too much would look 'unnatural' (whatever that means) and yet too little ....   Finally the colour.  No matter how I try, I just cannot bring myself to like teal.  

The subs were shot between 28 and 31 August 2017 on the dual rig at my home observatory in Notts (UK).

Details:

  • Williams Optics x 2
  • Moravian G2-8300 x 2
  • Chroma, Astrodon and Baader filters
  • Ha: 24x1200"
  • OIII: 31x1200"
  • Red: 5x600"
  • Green: 5 x 600s
  • Blue: 6 x 600s

Total: 21 hours

E_Smaller_Starsx1920.thumb.jpg.ffe42da394ba928d601fd5fbb3b4ee50.jpg

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Hi Steve, I agree with you it is very faint, I had a bash at this last weekend, but only managed 2 1/2 hours worth of Oiii and some of that was 600secs and some 600secs binned, I only managed to get the middle bit to show,  so your image gives me a bit of a yardstick.

What filters were you using for the oiii as you mention both Baader and Astrodon and what were the bandwidths.

Now back to your image, it has come out very well for such a faint object, I did manage to get the Ha regions a bit brighter but it's probably overstretched at this point.  I like the use of RGB to colour the stars, I might do that next time.  I like the colour of your squid.

If you're interested, this is my Squid which is currently residing in the staging area of Astrobin as a WIP.

http://www.astrobin.com/310171/?nc=user

Carole 

Edited by carastro
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Thank you Carole, the OIII was all shot through a Chroma 3nm.  My skies are OK, not properly dark, but I am probably reasonably fortunate where I am.  If I were doing this again, I might try 30 min subs, and I would probably want a darker sky.  

I see from your WIP that you aren't a fan of teal either.  :icon_biggrin:  My Ha was pretty good quality (if I do say so myself) and I had 8 hours of it.  But if I gave it full rip I figured that the Squid would be even more difficult to see.  You have some of it coming through though.  Look forward to seeing the finished article.

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Looks good despite the faint signal.  I found the OIII very faint as well--even with 30 min subs at F4.2.  I only collected 10 though and felt if I collected 20-30 it would fill out nicely.  Yours is much cleaner (I was plagued by noise in the blue channel).  I love the RGB stars.

Rodd

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Quote

I see from your WIP that you aren't a fan of teal either. 

Actually Steve I prefer your colour to mine, I always struggle to get a nice colour in blue.  Yes I wondered whether 30 min subs might be the way to go, but trying to get enough clear skies in a dark/darkish location would be a big ask.  I was imaging at F4.72 We will all have to watch each other's progress.

Carole 

Edited by carastro

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I managed to regain a bit more control over the stars with the Squid, itself.  I also allowed some teal to creep back into the picture:

C_Squid_HaOIII_RGB_FINx1920.thumb.jpg.a9f3ea39b914316533331145fc043406.jpg

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I love the blue. The squid shape almost has a 3D effect on it. Lovely. 

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This looks very good to me, I particularly like your processing of the star colours, how did you combine the RGB data with the NB ?

On the faint object point - is there any reason why you are limiting yourself to 1200s NB subs,  given your location I'd have thought that you would have selected 1800s as the standard NB exposure time ?

Alan

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Hi Alan, and thank you for your kind words.

The 1200s vs 1800s is an interesting debate.  I know Olly et al are supporters of the 1800s.  My Mesu is more than capable and I have done 1800s in the recent past (whether or not the EQ6 could do this is another matter). It adds significantly to the time, however - I have it in my head that I need a minimum 12+ subs to get a reasonable integration and that would mean a minimum of 6 hours instead of 4 hours.  Given the limited time we get here due to weather, skies and so forth, I have found mysel going back to 1200s.  I honestly don't know if the extra 10 mins would have made a difference - I doubt it.  Finally, losing an 1800s sub would be 50% more heartbeaking than losing a 1200s sub (although I must say the Mesu hasn't failed me yet, guiding-wise). I may try some 1800s Squid at some point, but for now I need some respite from it!

Adding the NB to RGB:

  • Split RGB image into channels
  • Add NB to chosen channel(s) using blend mode 'Lighten'
  • Recombine
  • You now have 'Ha to Red'
  • Take the 'Ha to Red' image, split it and then add OIII to Green; and, to a second 'Ha to Red', OIII to Blue
  • In PS start with 'Ha to Red' - layer 'OIII to Green' then 'OIII to Blue' on top
  • Adjust opacity sliders to taste

I should add that ths technique was shown to me by @ollypenrice  I hope that I have explained it correctly.

Edited by gnomus
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42 minutes ago, gnomus said:

Hi Alan, and thank you for your kind words.

The 1200s vs 1800s is an interesting debate.  I know Olly et al are supporters of the 1800s.  My Mesu is more than capable and I have done 1800s in the recent past (whether or not the EQ6 could do this is another matter). It adds significantly to the time, however - I have it in my head that I need a minimum 12+ subs to get a reasonable integration and that would mean a minimum of 6 hours instead of 4 hours.  Given the limited time we get here due to weather, skies and so forth, I have found mysel going back to 1200s.  I honestly don't know if the extra 10 mins would have made a difference - I doubt it.  Finally, losing an 1800s sub would be 50% more heartbeaking than losing a 1200s sub (although I must say the Mesu hasn't failed me yet, guiding-wise). I may try some 1800s Squid at some point, but for now I need some respite from it!

Adding the NB to RGB:

  • Split RGB image into channels
  • Add NB to chosen channel(s) using blend mode 'Lighten'
  • Recombine
  • You now have 'Ha to Red'
  • Take the 'Ha to Red' image, split it and then add OIII to Green; and, to a second 'Ha to Red', OIII to Blue
  • In PS start with 'Ha to Red' - layer 'OIII to Green' then 'OIII to Blue' on top
  • Adjust opacity sliders to taste

I should add that ths technique was shown to me by @ollypenrice  I hope that I have explained it correctly.

Yes an interesting debate - I'm currently experimenting with 1800s sub exposures in Lum on a faint galaxy at the moment but I do standardize on 1800s for the NB.

Thanks for the processing guide on the RGB blend into NB - I will definitely have to try this.

Alan

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Back again!!! I think this one is a little better again:

H_Squid_FINALx1920.thumb.jpg.f65b52f092b6b56979b93b0c3903cfc9.jpg

 

Edited by gnomus
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great image Steve :thumbright: i tried this last year i couldn't get any OIII to show at all. if i get chance i may try again now we have shielded led street lights 

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6 hours ago, toxic said:

great image Steve :thumbright: i tried this last year i couldn't get any OIII to show at all. if i get chance i may try again now we have shielded led street lights 

Thanks Chris.  I'm not surprised you couldn't see anything.  There was virtually nothing there even after I'd stacked it!  Good luck with your second attempt, but searching for Cthulu can lead to the Mouth of Madness.

6 hours ago, Petergoodhew said:

If I had a squid as good as that I'd be a very happy man.  I think that's splendid Steve.

Thanks Peter.  I think it needs one final tweak!!!!    :help:

Edited by gnomus
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what a cracking squid,

gnomus you have now gained the honorary title of squid tweaker

joking aside very nicely done, very natural looking.

Paul

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8 minutes ago, ultranova said:

 ......   you have now gained the honorary title of squid tweaker .... 

Ooooooh, Matron!

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I think it's a great image, particulary squid-wise. I don't think a more energetic haul on the Ha bowline would inhibit the presentation of the Squid at all. I'm inherently averse to noise reduction but every Squid I've ever seen, and certainly my own, has shown clear signs of NR. I think it's just something we accept in rendering visible a critter which, despite inhabiting well-trawled waters, escaped the net till a few years ago when Nicolas Outters landed it by accident. (He was expecting to find OIII signal in the Bat and thought, on seeing his first sub, that the mount had gone off task and pointed somewhere else in the sky.)

Perhaps, Steve, you feel luke warm about the image because you know how much NR and brute force went into it. (Assuming you treated your data in the same sort of way that I treated mine!) But in truth the result doesn't look tortured at all, it looks superb.

If I were you I would regard this project as a resounding success.

Olly

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1 minute ago, ollypenrice said:

I think it's a great image, particulary squid-wise. I don't think a more energetic haul on the Ha bowline would inhibit the presentation of the Squid at all. I'm inherently averse to noise reduction but every Squid I've ever seen, and certainly my own, has shown clear signs of NR. I think it's just something we accept in rendering visible a critter which, despite inhabiting well-trawled waters, escaped the net till a few years ago when Nicolas Outters landed it by accident. (He was expecting to find OIII signal in the Bat and thought, on seeing his first sub, that the mount had gone off task and pointed somewhere else in the sky.)

Perhaps, Steve, you feel luke warm about the image because you know how much NR and brute force went into it. (Assuming you treated your data in the same sort of way that I treated mine!) But in truth the result doesn't look tortured at all, it looks superb.

If I were you I would regard this project as a resounding success.

Olly

That is it exactly, Olly.  I know what is 'under the hood' so to speak.  Thanks again for your encouragement.

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12 hours ago, gnomus said:

..... I don't think a more energetic haul on the Ha bowline would inhibit the presentation of the Squid at all.....

I had a look and think you are right (again):

P_Squid_Sharp_FINx1920.thumb.jpg.e6c0220792547bbc93bcb8a3d4f13aba.jpg

 

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3 hours ago, gnomus said:

I had a look and think you are right (again):

P_Squid_Sharp_FINx1920.thumb.jpg.e6c0220792547bbc93bcb8a3d4f13aba.jpg

 

That works! The three dimensionality generated by the Squid in the foreground is enhanced still further. You have a winner.

I now need to brace myself for the purchase of a new OIII filter. 

Olly

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 Very nice Steve..... I think as you have processed it gives a real 3D feel and brings the top of the bat and the squid to the forefront. Love it :) Maybe next year for me...... so much in the pipeline :D

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Woah! Awesome image, the contrast between the Ha an OIII data gives an excelent 3D perspective. Wish I had a proper CCD to try this kind of objects :)

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Thanks Olly, Sara and Giskard_.  Olly sent me some behind the scenes suggestion - essentially urging me to be bolder still with the Ha.  This is it now.  I have to go and lie down....

R_Squid_Redder_FINx1920.thumb.jpg.28591b2c997b809ba51ec643f89e7e15.jpg

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