Centaurus A with QHY9 mono + M4 Glob + RAW DATA

[alpal]

I finally got my Varilock variable spacer well adjusted & managed
to get over 2 hours of 10 minute subframes of LRGB.
I used a 2" Astronomik CLS-CCD filter as this was from my light polluted driveway.
For the first time I actually got FWHM values of around 2.6
across nearly all the entire frames instead of the other night of 5.8 -
I checked each sub frame as I was shooting using Maxim DL.
It would have been good to collect more data to reduce noise.
I also took 3 x 2 minute subframes of RGB - as the small wells of the
QHY9 filled up quickly on the bright stars & I wanted to get star colors.
I copied the stack of bright stars into this photo from the 2 minute sub frames.
There is still a gradient problem so I may re-process but I am pretty happy with the result.

Taken with an f6 8" Newt.
A larger 1600 pixel version is here:
http://www.flickr.com/photos/2471943...n/photostream/

[jase (Jason)]

Good work, especially under suburban skies. You should be happy with that result. The gradients certainly do shift your colour balance. These shouldn't be too hard to correct. DBE in PixInsight would handle it well, as would GradientXterminator in Photoshop. All other technicalities are excellent. Round stars and great detail throughout the dark lanes. A sign your set up is work well. Would be great to see a repro post background neutralisation. Thanks for sharing.

[alpal]

Thanks Jase,
I think I will buy GradientXterminator.
I used Fitswork4 & that helped a lot as the gradient was quite bad.
The problem is that the secondary mirror is not quite centralized with the focuser
& of course shooting from a light polluted location.

I would have got more subframes but I couldn't force the EQ6 mount to
do a meridian flip & the OTA was nearly touching the tripod legs.
I still imaged past the meridian until that point.
Normally the EQ6 mount will realize that it's on the meridian &
when I go back to park & input the target it will flip automatically.
This time it wouldn't do it & there is no function in the Synscan handset to force a meridian flip.
It's available in EQMOD but I haven't loaded that program.

I had a good look at your website & the pics are amazing.

cheers
Allan

[jjjnettie (Jeanette)]

Gradient Exterminator is the bomb. I don't use it often, but I'm grateful to have it there to fall back on.

You've done well for a suburban location.

[alpal]

Thanks Jeanette,
I also took 40 minutes of data for M4 the globular cluster.
Larger version on flickr.

[alpal]

Would anyone like to process some RAW data?

I used 2 x drizzle on Centaurus A in many different modes
for all 12 x 10 minute files & found that median gave the best results.
I processed it & then used it as a luminance layer for my
picture & behold all of this detail popped out!

I have uploaded the RAW stacks for anyone wanting to process
this Southern hemisphere target.

Centaurus A

These first 4 are the LRGB at 600 second frames stacked:

https://www.dropbox.com/s/idy8r1svp6...20Lum_600s.TIF

https://www.dropbox.com/s/0g3j1zchvp...20Red_600s.TIF

https://www.dropbox.com/s/vmfz46a4e2...Green_600s.TIF

https://www.dropbox.com/s/0pmp4ch1ok...ue_%20600s.TIF


The next 3 are RGB at 120 seconds for purists who want to
get correct star colors on the many bright stars which exceeded the well depth.
Process for the star colors only -
then using this method if you want to in Photoshop:
Select color range, highlights, select modify expand by 4 pixels
& feather by 2, then play with curves & vibrance etc
then copy & paste into the original pic.

https://www.dropbox.com/s/muyqje220p...%20seconds.TIF

https://www.dropbox.com/s/ydt61gvenk...%20seconds.TIF

https://www.dropbox.com/s/9nsoyi2nhn...%20seconds.TIF


Next is a medium stack of 2 x drizzle on all of the 600s frames.
It can be used as a luminance layer to bring out more detail in the galaxy.

https://www.dropbox.com/s/55rrtm09z4vtwag/Stack%20of%20all%2012%20files_2%20x ...


Here is a reprocess of the last file placed as luminance on the galaxy.
Larger file here:

http://www.flickr.com/photos/2471943...ream/lightbox/

[Ross G]

Great photo Allan.

Sharp and detailed.

I like the colours and composition.

Your driveway is getting better and better!

Ross.

[alpal]

Thanks Ross,
If I could have forced a meridian flip I might have got another hour of data.

This is my latest version:

http://www.flickr.com/photos/2471943...ream/lightbox/

cheers
Allan

[Ross G]

Hi Allan,

The new version looks great.

I really like the "warm" colours.

Ross.

[alpal]

Thanks Ross,
I worked on the image a little more.
I wonder if anyone downloaded the RAW data?
Dropbox doesn't give statistics.

A 1600 pixel version is here but the full size Tiff is better:
http://www.flickr.com/photos/2471943...n/photostream/

[alpal]

Latest news on Centaurus A:

I finally learnt how to do flattening backgrounds properly using Fitswork 4.

see here:
http://intervalometer.appspot.com/Fitswork.jsp

I never knew about the
"Flatten Radius to 50 and "Mark Bright Areas" in such way that your objects become yellow as shown below."

& the fact that images with borders had to be cut with the scissors first - other wise it won't work.
This meant that I didn't have to buy GradientXterminator to get my backgrounds equalized.
What a difference it makes when you can get rid of gradients in the image!

I reprocessed both versions of the image including blurring
of noisy areas & iterative sharpening of selected areas
transferred in with a blurred layer mask just like
Ken Crawford shows in his videos.


fullframe:
http://www.flickr.com/photos/2471943...ream/lightbox/


Close up with the 2 x drizzle frame which was layered into the full frame just like a mosaic:
http://www.flickr.com/photos/2471943...ream/lightbox/

I am very pleased with the results now.
I feel like reprocessing many other images as I
have a handle on many new processing techniques.

[David Fitz-Henr]

That's a superb image Allan - great detail! Excellent work especially from a light polluted location. The only minor improvement I could suggest may be to fix the red rings around the cores of the brighter stars.

[multiweb (Marc)]

Great pic indeed. Very nice details. Just a tweak on the star ringing and you're good for the cool wall.

[astronobob (Bob)]

Extraordinary result form LP Sky Allan, dedication on your part is definatly credible, speshly with them processing techniques

[alpal]

Hi David, Marc & Bob,
Thanks for the kind comments.
I am still learning with this mono camera.

I think I might copy & paste the bright stars in again to improve them
& also - is my pic a little too red?
If I turn the red down the pic looks ever so slightly green which could be an illusion as the eye is more sensitive to green.

Next time I will use shorter 5 minute subs for RGB but at a binning of 2x2.
The L frames subframes of course at 1x1.
The only problem is aligning them in Deep Sky Stacker.
I'll have to try & use Maxim DL to stack which I think can do it but it's not as easy to use?


All advice is welcome.

cheers
Allan

[sjastro]

Very good image Alan.

Regards

Steven

[alpal]

Thanks Steve,
I just installed FITS Liberator 3 to use with Photoshop CS5.

see link:
http://www.spacetelescope.org/projects/fits_liberator/

I used the 32 bit FITS file of the 2 x Drizzle stack of all 12 frames.
I selected the white point as the brightest star &
stretched it in FITS Liberator using x^1/5.
I manually adjusted the gradient in Fitswork4.

I used it as a luminance layer on my image in flickr.
I had to blur the low brightness areas because they had noise.
The result was that a greater halo was revealed of Centaurus A.
I posted the pic on my flickr photos but here is a small
side by side comparison.
I will now use this method & work on the stretching only
with 32 bit FITS files as that is what Deep Sky Stacker produces.

Look closely & there is a larger halo on the right hand side.

[sjastro]

Thanks Alan,

I'll have to check out FITS Liberator 3.

Regards

Streven

[alpal]

Originally Posted by sjastro

Thanks Alan,

I'll have to check out FITS Liberator 3.

Regards

Steven

Hi Steven.
Yes it's worth downloading.
I like the results & it's faster than trying to stretch the image yourself.
I still had to manually adjust the gradient in Fitswork 4 - of course - but
I fixed all the LRGB before processing them.
I'll always use it from now on.
It's actually a stand alone program so can be used with any
processing package that will accept a TIFF file.
You start off with a FITS file & end up with a nicely stretched TIFF file.
I didn't think it would make much difference as the camera is 16 bit
but of course DSS outputs 32 bits.

I just redid the full frame & placed it on Flickr.
It seems to be better.

cheers
Allan