Using Star Tools to process M33 - help required

[danny093]

Hi,

I have been previously trying to processing data with demo version of star tools, with a view to buying the full version when I had learned how to use the program better and get some results, but until now I didn't really get anywhere and put this down to my data rather the program which I really like - so much so I have kept trying until I can get more proficient with it.

I am using a full spectrum mod Canon 1000d with CLS clip filter, so when I read on another forum about dcraw (using version 9.17), I converted my lights, flats, darks, and dark flats and stacked with the recommended DSS (3.2.2) settings.

For the first time I seem to be making progress, and although the image below may have room for improvement, it is satisfying to me that I seem to be getting somewhere.

M33 attempt.JPG (35.58 KiB) Viewed 5119 times

My workflow was to bin and crop after auto dev to see where problems are, perform wipe, develop, life - isolate, and color in a similar way to another workflow I also read about on these forums.

But I wonder if more can be done with the data and if possible please advise where I can make improvements (there are probably many things I can do, but I'm not sure where to start)

If someone would be in a position to have a look, my data can be downloaded from:

https://www.dropbox.com/s/1rryw7jqlmmwc ... b.FTS?dl=0

Any assistance would be greatly appreciated

Thanks and best regards

Danny

[admin]

Hi Danny,

You're definitely getting somewhere!
I had a look at your data.
Two things stand out - you have some strange gradient and there is some clear pattern noise visible (streaks). Though the latter may have been caused by forgetting to dither between frames, the 'lines' are quite distinct, so they could also be the cause of not applying bias frames correctly (or not at all).
Another thing is that your star colors seem to be off a little - there is an over-representation of red stars in your data. I'm not sure if that's due to some sort of chromatic aberration or has something to do with the full spectrum mod.

--- Auto Develop
To see what we got. We can see a blue bias, copious oversampling, stacking artifacts.
--- Bin
To convert oversampling into noise reduction.
Parameter [Scale] set to [(scale/noise reduction 35.38%)/(798.89%)/(+3.00 bits)]
--- Crop
Getting rid of stacking artifacts and framing the galaxy a bit better.
Parameter [X1] set to [125 pixels]
Parameter [Y1] set to [84 pixels]
Parameter [X2] set to [1277 pixels (-104)]
Parameter [Y2] set to [837 pixels (-83)]
--- Wipe
Vignetting preset and 'cut out' the core part of the galaxy from the mask.
Parameter [Dark Anomaly Filter] set to [3 pixels]
--- Auto Develop
ROI over galaxy. Experiment with what looks good to you. Don't worry to much about the highlights - focus on getting the faint detail visible that you want visible.
Parameter [Ignore Fine Detail <] set to [2.5 pixels]
Parameter [Outside ROI Influence] set to [15 %]
--- Deconvolution
Used 'Auto Mask', default parameters.
Thanks to binning the signal some more detail was recoverable.
--- Wavelet Sharpen
Used same mask as Decon.
Parameter [Amount] set to [286 %]
--- HDR
Tame preset.
Parameter [Dark/Bright Response] set to [1.75]
Parameter [Detail Size Range] set to [392 pixels]
--- Life
Isolate preset (full mask).
Parameter [Strength] set to [67 %]
--- Color
Tricky one - we know that the HII areas should be purplish, the core slightly yellower and the rest of the disk a bit bluer.
Parameter [Cap Green] set to [To Yellow]
Parameter [Dark Saturation] set to [5.30]
Parameter [Blue Bias Reduce] set to [1.18]
Parameter [Green Bias Reduce] set to [1.29]
--- Wavelet De-Noise
Parameter [Scale 1] set to [80 %]
Parameter [Color Detail Loss] set to [14 %]
Parameter [Grain Size] set to [10.2 pixels]
Parameter [Read Noise Compensation] set to [4.13 %]

And this is the result;

m33calib.jpg (188.48 KiB) Viewed 5103 times

It's just my interpretation of your data, but by no means gospel! Hope this helps...

[danny093]

Hi Ivo,

Wow, that's great, thank you!!

Now I know what can be done with Star Tools in the right hands with my data I will definitely be getting the full version

I have just got a 0.85x reducer for my SW120ED so hopefully that will improve the oversampling a bit. I also have some concerns about amp glow so plan to get a serial trigger cable for my 1000d for use with APT software (at the moment i am not using mirror lockup with liveview via APT as amp glow is definitely a problem then). I guess one way to identify the fault is to try out my 500d unmodded with the CLS CCD clip filter on the same target and see how both match up.

I have some bias frames from the run that I left out, instead relying on the bias in the dark flats to remove pattern noise. I think I will try and follow some other advice on another forum and try some different stacking combinations to see what works best. When stacking in DSS, would you recommend average or median method for bias, flats, and darks?

This is the first time I have had someone who knows what they are doing have a look at my data so all this is really very useful for me, thank you.

Best regards

Danny

[admin]

Hi Ivo,

Wow, that's great, thank you!!

Now I know what can be done with Star Tools in the right hands with my data I will definitely be getting the full version

Glad you like it. Again, your version is not bad either, given the data. I guess mine is a bit more aggressively stretched, which is a matter of taste.

I have just got a 0.85x reducer for my SW120ED so hopefully that will improve the oversampling a bit.

Nice! It's good you now have a little flexibility then. Oversampling is not necessarily a bad thing as you can see we can use it to reduce noise. But having the option of a wider field using the reducer is always nice and can definitely help with some objects.

I also have some concerns about amp glow so plan to get a serial trigger cable for my 1000d for use with APT software (at the moment i am not using mirror lockup with liveview via APT as amp glow is definitely a problem then). I guess one way to identify the fault is to try out my 500d unmodded with the CLS CCD clip filter on the same target and see how both match up.

I'd be very interested to see the comparison - it may help others as well. I'd also be interested to see the difference in terms of colour - pretty keen to find out what is causing the red halos around most of the stars...

I have some bias frames from the run that I left out, instead relying on the bias in the dark flats to remove pattern noise. I think I will try and follow some other advice on another forum and try some different stacking combinations to see what works best.

Did you dither between frames? After flats it's the easiest way to enhance your data in leaps and bounds!

When stacking in DSS, would you recommend average or median method for bias, flats, and darks?

I'd probably go for median (if you have more than a few frames).

This is the first time I have had someone who knows what they are doing have a look at my data so all this is really very useful for me, thank you.

No worries! I can also highly recommend hopping up on a forum like CloudyNights or AstronomyForum.net. Lots of really helpful folks there.

Clear skies!