10 Hrs on M81 and M82

[symmetal]

During the clear spell last week I managed to get 10 hrs worth of data on M81 and 82 using an FLT98 + 0.8 reducer and Atik One 6.0 CCD. 16 x 10 min each of RGB and 28 x 5 min of L.

Stacked in Astroart, registered with Registar and processed with Startools and PS. I was wondering whether I could see the dust lanes as seen in other images and while they were visible they were noisy so I've just shown a hint of them and used Olly's trick of flattening the PS curve just below the level of the dust to remove a lot of the noise. 😀

The very bright stars tended to be composed of coloured rings so I blurred the centre of those stars as a separate layer in PS and substituted mono versions of the stars on another layer of those that were beyond help. The two bright stars bottom left also had two very noticible diffraction spikes on just the red channel  so there may be a hair on the filter or something. I've hidden the spikes reasonably well.

Just to the left of M81 there is a smudge which is actually Holmberg IX, a dwarf irregular galaxy of magnitude 16.5 and is a satellite galaxy of M81.

This is on my dual rig with the other one being an ASI 1600 and a ZS61 so I have the same amount of data on that minus those spoiled by dithering the Atik images. While it's a significantly shorter focal length the smaller pixel size means the difference in imaging scale is not that great. I'll process that later to see how the CMOS camera compares to the CCD. 😀

Alan

[astro mick]

Well for all your problems Alan,still a very nice image.

Mick.

[MarkAR]

Excellent image.

[symmetal]

30 minutes ago, astro mick said:

Well for all your problems Alan,still a very nice image.

Mick.

Thanks Mick.

Startools is very good for maintaining star colour as all processing steps are done on linear data but I seem to end up with stars of multiple colours for very clipped stars. I normally use the automatically generated masks in Startools but it might be worth manually modifying them to control their processing. It's probably easiest just doing a simple stretch in PS to get the best clipped stars and layering them over the Startools image.

Alan

[astro mick]

I,ve never quite mastered Startools,may have to dig it out again,not many Tutorials on this software.

Mick.

[symmetal]

I removed the filter wheel from my Atik One and found this on the red filter which I hope is the cause of the diffraction spikes on just the red. There was also a film over most of the red filter which wasn't present on the others which may help to explain the pattern, again only on red, around the highly clipped stars similar to what you get to a larger extent with dew.

Now cleaning it, so fingers crossed it'll improve it. 😀

I've tried the latest beta version of Startools which was has many changes and several extra features over the standard stable release. One of these is 'Highlight Repair' on the 'Colour' module which is to remove coloured fringing around saturated stars. This worked very well on the smaller clipped stars basically desaturating the star edges but the above star was beyond help in that respect.

3 hours ago, astro mick said:

I,ve never quite mastered Startools,may have to dig it out again,not many Tutorials on this software.

Mick.

The Startools site forum has several links to instructional videos which may be useful. The manual is a bit out of date and incomplete but in the program clicking the help button on each module gives a web page of an explanation of what it does. Each adjustable parameter on each module has an '?' button which gives helpful info on what it does too. 

Alan