Bubble Nebula HaRGB

[cfpendock]

Because of the weather, this project has been on the go for about six months now.  I am afraid that I got too impatient waiting for clear skies, and finished it on the night of the 15th Dec - the first possibility I've had since September.  The visibility was not good, and the price of course is a less than perfect image.  The image is comprised of Ha (Baader 7nm): 18 x 20 minutes) and RGB (16 each at 5 minutes), and was taken using a focal length of 850mm in an attempt to provide good detail within a reasonable field of view.  This gave less than around 1.8 arcsecs/pixel.

 

The Ha was blended at around 60% into the red channel.  Processing has proved extremely difficult - I like to think that the raw data was not very good due to bad seeing conditions, but I'm afraid this may be just an excuse for poor processing skills.  

 

1.There is considerably more detail available in the nebula, but trying to bring it out makes the image very noisy, despite the number of subs. At the same time, the nebula seems to cut off very sharply - although I took care not to clip any data.

 

2. The bigger stars are fuzzier and not as sharp as I would have liked.  Is this due to poor seeing?  Guiding generally seemed OK - less than one arc second.  Focussing also seemed correct, there was very little change over 40 minute refocussing periods.  Or is there a magic way to reduce star fuzziness when there are a lot of stars needing attention? 

 

Ah well, it was fun doing it…….  Any processing help would be very gratefully received.  

 

Chris

 

[Cozzy]

very nice image given the poor condition you had to contend with.

What camera did you use?

Tim

[cfpendock]

Thanks Tim.  I used an Atik 4000.  

Actually, I was shocked to see the degradation in image quality on this site, both in colour and detail.  I understand PNG files are better, but saving this image as a PNG results in 17MB, and my internet speed won't cope with that…even reducing to 8 Bits still results in 4MB.  So JPEG…...

Chris 

[ultranova]

As said very good under poor conditions, The way the site shows the images will reveal

any flaws in the picture, what looks ok on your home screen might not quite look the same on here,

Unfortunately, any poor stacked images will show up in the end result, there's know way around this

unless you try and stack only the subs you are confident with.

Paul