bi-colour M27 - what on earth is happening here ?

[powerlord]

So.. quicky last night between the rain. 6 10 min ha subs, 1 oiii sub.

so - work in progress.

'stacks' attached. But processing in startools, this is the best I get.

I seem to have found a whole bunch of Ha which looking at other pics of M27, just does not exist. Any ideas what I'm doing wrong ?

C8, .67 reducer/corrector, asi1600.

21.08.08.M27-Oxygen_III-session_1.fits21.08.08.M27-Hydrogen-alpha-session_1.fits

[vlaiv]

5 minutes ago, powerlord said:

I seem to have found a whole bunch of Ha which looking at other pics of M27, just does not exist

It does exist, but is faint and most people don't manage to capture it.

If you do a quick search on google - you'll see quite a few examples that managed to capture it:

[alacant]

Hi

Nice image. Loadsa detail.

Are you sure you composed the channels and their weighting correctly?

Flat frames aren't really discretionary though, even for a wip, as they make processing much more difficult than it need be and this in turn makes it harder to see what's needed next.

TBH, I think this is gonna be good. Just keep collecting frames. Oh, and of course learn the StarTools compose module;)

Cheers

Edited August 9, 2021 by alacant

[powerlord]

Hmm, well I read the manual, but can't say it was clear.

The way I read it, for bi-colour (I will be adding Sii but its what i have for now), load Ha as R, Oiii as green. So did that, and selected  the "L + Synthetic L from RGB, R(GB)(GB) (Bi-Color)" scheme.

For colour module I ran through em all, but HOO was what I was aiming for. I fiddled with the bias but couldn't get it to look right at all.

But looking at what I assume is my processed pic by yourself, I obviously screwed something up.. though I did go through it all about 3 times 😕 From the above is it obvious what I did wrong ?

But yeh, your one is what I expected to see at this stage, so looks like my data is ok. And I'm already getting those outer shells even with one 10 min Oii, so yeh I'm hoping I can build on that and end up with something nice. 20% cloud cover tonight, so will probably give it another punt... though last night it said the same till 2am then 100% clouds - but  zero chance of rain till 9am or later.. But didn't get cloudy till 4am in the end - so lost imaging time I could have used there (mount sitting there 2-4 doing nowt).. but as I was up, I took all the kit inside. At 7am the heavens opened and it pished down!! bloody weather forecasts.

[alacant]

15 minutes ago, powerlord said:

is it obvious what I did wrong

No.

I took the bi-colour default without channel interpolation so I had only red and green and then chose linear to close the compose module. I then discovered the absence of flat frames so I had to crop tightly to remove the vignetting and associated circular gradient. Or I suppose you could try the synthetic flat algorithm in wipe.

Apart from that, the bi-colour preset with boost to dark saturation in colour and a tight crop on core for the second AutoDev. Otherwise, the defaults.

A good rule with ST is that if you've been going at it more than 10 minutes and it still looks hideous, roll back before the wipe and redo the stretching development. 

Cheers and HTH 

Edited August 9, 2021 by alacant

[powerlord]

thanks. yeh flats were not an option as the filter wheel hit the wifi adapter on trying a meridian flip. when I got out there at 4am I found it stuck against it, and it had sort of loosened the filter wheel which had rotated 😞

Some re-organsing is in order for it not to happen again, so will probably have to bin those subs in the end. It's a pain that asiair doesn't give you a way of testing meridian flips. I'll need to just try selecting something as close to meridian as I can and wait so I can actually test the thing.

I am getting guiding around 0.3" rms with the EQ6r-pro now though after some tweaking, but I still don't think the C8  is as good as it should be, but I'm now loath to touch it now that stars actually look like stars. I also had major issues with condensation last night even with dew heater - had to clean it off every 30 mins or so, once I realised it wasn't actually getting cloudy.. it was dew...

Good tip about going back to start - though usually what I end up doing is giving up after a couple of goes, and retreating to Affinity Photo! 🤪