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Horsehead Nebula from Bahrain

Farooq

By Farooq
in Imaging - Deep Sky

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Farooq

Farooq

Posted
Posted

Winter here is a welcome change from the hot weather and humid nights. Temperature is now around 15degs in the evenings ideal for getting the CCD down to -10 degsC and less. I managed to get a few sessions at the Horsehead nebula.

I took 9 x 900s Ha, and 6x480s RGB, I was also able get 6x600s L as well.

I tried 2 approached to processing, Ha-HaR-G-B and L- HaR- G-B.

I would welcome comments and feedback on how I could improve upon them.

post-21564-0-90340100-1356358680_thumb.j post-21564-0-25732000-1356358703_thumb.j

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James

James

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That's a lovely image - the Flame and the Horsehead look great - I really like the difference in colour between the Flame and the area around the horsehead in the first picture:)

I prefer the first image myself. The second image has some green colour gradients.

James

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ollypenrice

ollypenrice

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Did you shoot flats? If so, I don't think they are working well and if not you need to do so! There seems to me to be a gradient in the greens, maybe the green or O111. The first process plays this down a great deal.

But it has lots to say.

Olly

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Farooq

Farooq

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Did you shoot flats? If so, I don't think they are working well and if not you need to do so! There seems to me to be a gradient in the greens, maybe the green or O111. The first process plays this down a great deal.

But it has lots to say.

Olly

Cheers Olly, yes you qre right about the flats

I took flats for the Ha, but not for the RGB. I tried using various tools such as Gradient exterminator and the gradient removal function in MaximDL without too much success for removing the gradient removal.

I have a Flat panel, but despite adding layers of thick card in front of it to dim it down,it is still too bright. For the SBIG ST8300 the ADU for flats is supposed to be around 8,000 and exposures normally around 3-4 secs from what I have read on forums. For the Ha the flats are around 4secs, but I cannot see any dust motes etc, or heavy circular gradient.. I can see gradient around the edges and thats about it.

I agree there is no substitute for flats, however if I was to try and remove the gradient using tools such as gradient exterminator or other tools such as some of the PS actions, at what stage during the processing process do you try to remove the gradient. Straight after calibration and before non-linear stretching or after ?

Cheers

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ollypenrice

ollypenrice

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Cheers Olly, yes you qre right about the flats

I took flats for the Ha, but not for the RGB. I tried using various tools such as Gradient exterminator and the gradient removal function in MaximDL without too much success for removing the gradient removal.

I have a Flat panel, but despite adding layers of thick card in front of it to dim it down,it is still too bright. For the SBIG ST8300 the ADU for flats is supposed to be around 8,000 and exposures normally around 3-4 secs from what I have read on forums. For the Ha the flats are around 4secs, but I cannot see any dust motes etc, or heavy circular gradient.. I can see gradient around the edges and thats about it.

I agree there is no substitute for flats, however if I was to try and remove the gradient using tools such as gradient exterminator or other tools such as some of the PS actions, at what stage during the processing process do you try to remove the gradient. Straight after calibration and before non-linear stretching or after ?

Cheers

You can only use Grad X or Ps on the stretched image otherwise you can't see what you're doing. By far the most powerful of these tools is Dynamic Background Extraction in Pixinsight. This remarkable routine operates on the linear image while giving you a screen stretch showing what will happen once the linear image is finally stretched after the routine has been applied. This is very clever! However, any of these routines will struggle on an image as full of nebulosity as this one. What are you going to define as background sky? Is there any??

You will be able to dim your panel down enough. You may just need more diffusers, maybe a perspex panel. You can even use a clear perspex one if you sand it very thoroughly and evenly on both sides. Remember that with a shutter camera flats must be on longish exposures or the wipe of the shutter blade will register as a gradient. I don't know how long they have to be. Three seconds? Not sure. (Could this be your problem?) I think you could go above 8000 counts but you're right.

I'd also advise you to use your panel in the dark. I have never yet got decent flats in the daytime, even in the closed observatory. They always introduce a gradient. Very odd, but that's what I find.

Olly

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allcart

allcart

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Sorry Laser, no offense intended, but I think you overcooked it. Its too smooth now and has lost detail. There are also halo's around the stars which were not apparent in the original. However, the noise and gradient has been removed.

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Farooq

Farooq

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Adding to the LRGB image I took last year, I have tried imaging the horse head nebula in narrowband only.

I still can't get the HST colour balance right yet. Below is my attempt somewhat feeble attempt at the Horsehead nebula through Ha and OIII processed bicolour and also Ha/OIII/SII processed using HST palette.

The below images are with the subs which I have taken so far which are  1800s each,   4 x Ha, 3 x OIII, and only 2 x SII so far. I need to get many more subs to get rid of the noise and improve signal.

post-21564-0-00755800-1384463340_thumb.j          post-21564-0-47607000-1384463408_thumb.j

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doseri

doseri

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Posted

Winter here is a welcome change from the hot weather and humid nights. Temperature is now around 15degs in the evenings ideal for getting the CCD down to -10 degsC and less. I managed to get a few sessions at the Horsehead nebula.

I took 9 x 900s Ha, and 6x480s RGB, I was also able get 6x600s L as well.

I tried 2 approached to processing, Ha-HaR-G-B and L- HaR- G-B.

I would welcome comments and feedback on how I could improve upon them.

attachicon.gifHa_HaRGB 800x600.jpg attachicon.gifL-HaRRGBcolor small bluestars PS.jpg

hi 

i think you need more image to stack for the noies, and flat  go  more withe adu about 18000 ,from where do you take you image  ( من البر)  i do same in there too, but you mast go  way from street lights

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