NGC2280 - Please critique.

[ChrisD (Chris)]

I did a quick search and I think this may be the first time NGC2280 has appeared on Ice in Space. Correct me if I'm wrong.

I found some time to reprocess subs taken around 2 years ago. I wasn't happy with the first attempt back then, so I tried again.

25x600sec OSC subs from a ASI294MC Pro. C8 on a HEQ5.
Processed with Pixinsight.

I'd like some critical feedback on the results. Where can I improve.

Thanks
Chris

[gregbradley]

That is a good capture. As you say I don't recall seeing this one before.

Stars are a bit large which is common for SCT scopes. BlurXterminator or Starshrink would help there.

The colour of the spiral galaxy looks too greyish. Typically they have a bluish colour in the spiral arms. Try to tease out the bluish tones that are undoubtedly there.

Love the faint disturbed spiral arms you picked up.

Greg

[Stephane]

Hi Chris, processing wise I think you’ve done a great job! Image acquisition is excellent too with nice round stars even in the corners. My only observation is that this target would benefit greatly from more integration. You’ll be able to draw out this faint arms so much more without worrying about noise. Not to mention a cleaner and less hazy looking background.

Overall, an excellent result for 4h10’.

[astro744]

Originally Posted by gregbradley

That is a good capture. As you say I don't recall seeing this one before.

Stars are a bit large which is common for SCT scopes. BlurXterminator or Starshrink would help there.

The colour of the spiral galaxy looks too greyish. Typically they have a bluish colour in the spiral arms. Try to tease out the bluish tones that are undoubtedly there.

Love the faint disturbed spiral arms you picked up.

Greg

Ditto. Likely to be some pinks in there too.

There is a star at upper left with a halo on its left side. Is this a real object or an imaging artefact of some sort?

[Dave882 (David)]

Nice job yeah not a target often imaged and you e done really well. Data looks pretty good and lots of detail however I think the noise reduction may have smoothed over some of the detail in those outer arms. More integration will help things. Colours are a bit muted so reckon even with your current integration there could be more in there to be drawn out.

[alpal]

Excellent picture Chris,
the colours compare well with this ESO pic:
https://www.eso.org/public/germany/i...280-potw/?lang


I agree with David that there is too much smoothing of the noise -
the faint arms would look better showing some noise.


cheers
Allan

[PRejto (Peter)]

I think you have some decent data on the galaxy. Great. I think others have made good suggestions re colour and smoothing. My comment is the stars....they look blown and blobby and to me are not round enough in several places. Is this tracking or optics (coma, tilt, etc)? The image would look great I think if you took a bunch of shorter exposures just for the stars. The brightest stars may still blow out no matter what you do, but the medium brightness stars should not and you ought to be able to get some great colour and smaller stars. Once data is blown there is no colour data left! (Just on the very off chance that you don't know the word "blown" it is when your wells on the CCD/CMOS are totally filled and additional electrons cannot be captured - hence short exposures.) Just replace your old stars with new...

Peter

[ChrisD (Chris)]

From the responses I've several areas I need to improve.

1. Some stars in the corners are not as well formed as I would like. I think I need to look at the backfocus from the flattener.
2. I appear to be loosing colour in the stars when I stretch. I'll try to find a better workflow to maintain colour throughout processing.
3. I will reduce exposure time to 120 sec and increase the number of subs. Less blown out stars and more detail in the nebula.
4. I'll try masking the smoothing to reduce the smoothing around the galaxy. Also reduce the amount of smoothing generally.

I'm also thinking of shooting some shorter subs with a dual-band filter and then use the Ha component as the luminance for the stars in the RGB image. This Ha lum would give me smaller RGB stars and be less likely to be "blown out". It tried this out on some other data I had and the results look better.

Thanks all for your comments.

Chris.

[DJT (David)]

Hi Chris
Some good ideas generated here and great to see a new object.

Peter mentioned stars and one of his questions was how good was the tracking.

If the tracking isn’t great the stars will be bloated as the mount bounces around so whilst shorter subs for stars might reduce that at the same time it might be worth checking how the guiding is going as all shorter subs might be doing is hiding a problem earlier on in capture though it will solve the problem of star cores being blown out. (10 minute subs will do that)

If the stars aren’t tight ( well focused and good guiding ) you are loosing detail in the galaxy though what you have is a great start.

D