Light pollution- horse head nebula

Questions and answers about processing in StarTools and how to accomplish certain tasks.

Light pollution- horse head nebula

Postby Jaume » Sun Oct 28, 2018 2:16 pm

Hi
I'd like your opinion about how can I process this two pictures. The pictures were taken from my house in Barcelona and have a lot of LP.
The objects are ALnitak with flame nebula and (I supose) there is the Horse Head Nebula too (But i can't see) :( .
I give you the stacked images in two FIT files.

The first is :
https://drive.google.com/file/d/1botGg1 ... sp=sharing

There are 110 Pictures stacked whit DSS (groups of ISO 200 and 60", 180") Exposure 05 hours:25':27"
Vixen R200SS, mount NEQ6 Pro with autoguide (20 Darks, 20 Flats, 20 Bias every group), IDAS Filter

the second is :
https://drive.google.com/file/d/1qxCmbY ... sp=sharing

There are 408 Pictures stacked whit DSS (groups of ISO 200 and 1600 and 60") Exposure 03 hours:23':19"
MAK127 , mount NEQ6 Pro with autoguide (20 Darks, 20 Flats, 20 Bias every group) IDAS Filter

I was trying to process then with diferent sequences that I saw in the forum, But without success.

Is anything wrong in the pictures (apart of LP)?

Can You help me?

Thanks
Jaume
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Re: Light pollution- horse head nebula

Postby devonshire » Sun Oct 28, 2018 10:46 pm

Jaume,

Caveat: I just recently got help with a polluted image, so I'm no expert (but I did just process my own Flame/Horsehead, so I'll run with it :-)

I looked at both your Mak and Vixen images, and took a run at them in StarTools. The Vixen one looks to me like there's a real problem back at DSS, and while the Mak starts out better, I wonder about it as well. I don't think the Vixen image should be a bright moire...

Questions:
What version of DSS are you using?
What did you use for DSS settings, and how did you save your files?
Did both images use the same DSS settings?

Hope this helps...

- Bob
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Re: Light pollution- horse head nebula

Postby devonshire » Mon Oct 29, 2018 3:06 pm

Jaume,

I took a second look at your images this morning. I can't do anything with them, but here's some things to think about, FWIW.

The Vixen image looks to me like it's first problem is a stacking issue of some kind. That white moire doesn't look right to me - should be black, with just a small sprinkling of stars. If both the Vixen image and the Mak image are fresh from stacking runs (w/identical params), it's odd that the images are so different.

The Mak image isn't a moire, but there's prominent light on one side. The Vixen has that, too, but much less. I wonder if you are picking up some terrestrial photons, on top of unwanted skyglow? Are you using a dewcap/light shield with the Mak? If not, that might help a bit.

I'm also wondering if having those ISO 1600's in the stack is a good idea. Might try re-stacking just the ISO 200's and see what you get. I'm under 'Orange' skies, and a 60 second ISO 1600 image would be far too bright for me at f6.1. Not sure what f-ratio your Mak is, but it might be easier to stretch a dim image up than to push unwanted skyglow down...

One last thing... It may not be necessary to invest mega imaging hours to test your setup and workflow for this target. I did a very brief shot of this region a few nights ago - just a few minutes, and just as a proof-of-concept for a later 'glamor' shot. I was surprised at how much detail I did get, and it was quite good enough to set me up for a longer run later.

Hope this helps,

- Bob
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Re: Light pollution- horse head nebula

Postby Jaume » Mon Oct 29, 2018 4:18 pm

hi
Thanks for your opinion.
I use the last version of DSS in the web. Te configuration is that one --> https://blog.cielosboreales.com/apilado ... startools/

Your comment about terrestial fotons, made me think about the posibility of ligth contamination from muy computer screen because usually I put the computer at this side of the telescope.

It's a silly idea but until your observation I did not think about it. :oops: :shock: :doh:

I will be carefull with the computer screen ligth the next session :!: :!: :)

Thanks :thumbsup: :bow-yellow:
Jaume
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Re: Light pollution- horse head nebula

Postby devonshire » Wed Oct 31, 2018 4:48 pm

Jaume,

Kind of quiet around here... I was expecting more would jump in.

Regarding DSS settings, that's always 'fun'. If you do a startools forum search on "DSS", you'll find a number of posts with settings advice (some of which seem to go back and forth a bit over time - and then, of course DSS changed a bit during its recent renovations...). Anyway, I've bumped my DSS settings around a bit and am finally more or less at peace with it, but then I'm on Nikon and I assume you're on Canon?

Best I can suggest at this point to help you move a bit farther along, is to experiment w/re-stacking the Vixen run on revised settings, and see if you can get from a white moire to black with a few sparkles.

Hope this helps...

- Bob
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Re: Light pollution- horse head nebula

Postby Rkonrad » Wed Oct 31, 2018 5:33 pm

Hi Jaume,

I tried to process your data to a dead end. Hopefully you can recover all that time to took to acquire the data! It may have something to do with your stacking or like you said - the other issues. I don't think this is a StarTools issue though Ivo is brilliant with this kind of stuff. I also recommend you to visit other sites (like cloudy nights) to see if they have pointers on your issues. Lot's of friendly people out there!

Richard
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