Melotte 15

[NoelC]

An image from last year now (12th & 13th of December)!
Took a bit of fiddling with to get anything out of it:


Spent ages taking it in RGB, but ended up using the Ha and OIII only.
This is the center of the Heart Nebula (right ventricle).
Atik One 6 on Altair f8 RC at 0.6FR, 600S OIII & Ha x 10 each.
Processed in APP- registration and colour combination tools work really well. Sretched in PS2.

[Carole]

Great work Noel.  Also some great star colour there.  The only thing I will say is you have over stretched a little burning out the stars a bit and some the the nebula.  Also colour saturation is just a bit OTT making the outer edges of the stars just a bit too bright.

An excellent leap forward since your last image.

I agree that this target works better in Ha and Oiii than in RGB, though you could use the RGB for the stars only.

Would love to get my hands on this stacked data and have a go at it myself.

Carole

[NoelC]

Thanks Carole

There is something going on with the stars (maybe dew on the primary?).
There are hot pixels everywhere; I did bias, dark and flat these, shouldn't that have got rid of them??  How do you use a bad pixel map to remove them?

Here's the stacks (there's a sat track on the OIII) they are 23MB.
http://www.filedropper.com/st-med-54000s-sc130none-x10lz3-ns-full-eq-add-scbwmvnor-aa-rl-nombb-hydrogen-alpha
http://www.filedropper.com/st-med-60000s-sc130none-x10lz3-ns-full-eq-add-scbwmvnor-aa-rl-nombb-oiii

[Carole]

Darks should definitely remove the hot pixels.  Dithering should also help with this if you are dithering.

I don't know how to use a bad pixel map I am afraid.

Will have a go at those stacks.

Carole

[Carole]

The files you attached are already stretched, have you got the unstretched files?

Carole

[NoelC]

Wow Carole!
(Carole's re-processing of my data)-

(This is the same data as the previous image but given the Master's Mistress's touch.)

That's just amazing.
I'm not aware of having stretched the data after stacking prior to saving; it does go through normalisation and background neutralising as part of the stacking process. They look un-stretched to me in AA5 - but   The subs were dithered, I think I am dithering by 3 pixels. Darks are based on 20 subs of the same length (600S @-20). Not using flat darks, one bias master (based on 20 or 30 subs of .001S).
How did you do that?
Noel

[Carole]

Hi Noel, I did not like to post it up myself, so E mailed it to you.

How did you do that?

I think you firstly have a tendency to try to keep the sky background too dark and therefore you are losing a lot of the background nebulosity.

The main feature was difficult to control trying not to lose the detail. 
Then I did selective colour control, and a selective High pass filter to bring out some of the fine detail.

When I stretched the colour in the stars I did that selectively, img/adjust/colour range/highlights, having previously made a layer so I could rub out anything that went too far OTT.
Little bit of despeckle and magic wand background noise reduction.

I tried to do the same colour red as yourself but failed.

Carole

[RobertM]

Noel,

You say that you're dithering by 3 pixels but is that with the guider ? If so then it may equate to many more pixels at the imager.  If it's 3 pixels at the imager then I would say that should be more like 5 or more.  I think I have mine set at about 6 at the guider (12 at the imager) though it probably doesn't need to be quite that much.  Dithering can waste quite a bit of imaging time so that's one reason not to set it too high.

I would certainly agree with Carole about setting the background too dark, it's a common issue I see with images.  I would tend to show the background a tad lighter than Carole did but the downside is that noise has to be quite well suppressed by data quality and or subtleness in processing.  It all down to personal preference... beauty is in the eye... etc.

PS. Wish I had a magic wand for image processing !

Robert

[NoelC]

Carole
Thank you very much! Am off skiing tomorrow, but will give it another go when I'm back.

Robert
Not sure how to answer that, as I just set it in APT (suspect I used the default).  It takes 30 seconds or so to settle each time, but the hot pixels seem to come through it, even though I'm median stacking, possibly not enough subs (10 in this image).

With you on the magic wand, thanks for your comments and help.
Noel

[ApophisAstros]

superb job Noel , love it.
Roger