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First M31


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Not necessarily that pleased with this one (neither capture nor processing), but as it's my first Andromeda, I thought I'd post anyway and hopefully will be able to show improvement in subsequent attempts. 

A bit over 7 hours integration, with the vast majority in L and only around 40 mins each R, G and B. Hopefully will be able to shoot some more frames over the coming months before Orion starts to take my attention away.

As always, comments and critisms welcome.

M31 LRGB.jpg

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Nice image.

I don't particularly like star reduction that you performed (or at least that is what I think that happened - all stars are tight but there is halo around them, galaxy cores also look funny), and I don't like plasticky feel to the background.

There is also central bit that has very strange red cast - maybe flats issue for red channel?

I know that there is pressure to show as much as you can from the data you have, but maybe try processing it less aggressive. Don't worry if your image does not show full extent of galaxy or whatever.

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12 minutes ago, vlaiv said:

Nice image.

I don't particularly like star reduction that you performed (or at least that is what I think that happened - all stars are tight but there is halo around them, galaxy cores also look funny), and I don't like plasticky feel to the background.

There is also central bit that has very strange red cast - maybe flats issue for red channel?

I know that there is pressure to show as much as you can from the data you have, but maybe try processing it less aggressive. Don't worry if your image does not show full extent of galaxy or whatever.

Can always rely on you to spot all the issues! 😉

The background is one of things I was not very pleased with. I used Startools and l think it has a tendency to cause this type of background when the data is pushed too far. I probably should, as you say, be a bit more conservative with the processing.

There was also indeed an issue with the red flats (and to certain extent, lum as well). I need to do a little investigating to find out why they didn't quite work. Unfortunately I've since disturbed the imaging train, but as it's only 40 mins of data, I think I might just throw it all away and redo the red channel entirely.

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1 hour ago, The Lazy Astronomer said:

The background is one of things I was not very pleased with. I used Startools and l think it has a tendency to cause this type of background when the data is pushed too far.

I find the same thing with Startools. It is one of the reasons I tend to find it gives less pleasing results with nebulae. If I do use it I normally use Astroflat Pro to reduce the fragmentation in the background. I some cases I use the manual develop module instead of the autodev as this stretch can be reigned in a little.

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6 hours ago, The Lazy Astronomer said:

comments

Hi

Very nice detail. Well done.

3 hours ago, The Lazy Astronomer said:

Startools and l think it has a tendency to cause this type of background

Strange. That shouldn't happen. Did you do anything to the data before you loaded into st? Maybe have a look through the dataset dos and donts?

Post a -link to- the data if you like.

Cheers

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On 05/10/2021 at 22:57, alacant said:

Hi

Very nice detail. Well done.

Strange. That shouldn't happen. Did you do anything to the data before you loaded into st? Maybe have a look through the dataset dos and donts?

Post a -link to- the data if you like.

Cheers

Thanks alacant. I follow all of the recommendations to get the data ready for st, but I find this tends to happen when the data is perhaps pushed further than it really allows, in combination with lazy/poor use of the star reduction and superstructure modules. It's definitely user error - I'm going to reprocess when I get the time to grab some more colour data (and redo the red channel completely, as it has not calibrated well).

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47 minutes ago, The Lazy Astronomer said:

when the data is perhaps pushed further than it really allows

Hi

The big strength of st is that if you have inadvertently gone too far, it's easy to go back to AutoDev and go again. No need to start over from zero. Go as many times as you need:)

if you're finding subsequent modules produce artefacts, that could not only simply be a sign of poor choice of ROIs but also poor  calibration/stacking or that the data itself is not that good.

in your case, clearly the quality is there. If there's detail, ST will find it like no other. What I'd recommend is looking at the calibration process again.

Cheers

Edited by alacant
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