Crescent Nebula - NGC6888 - Combined data from Televue Genesis and Vixen VC200L

[RichieJarvis]

Hi All,

Last night, I was feeling impatient for the subs to come down (as usual.) After a week of cloud, and only getting 4 Ha 10 minute subs last night, I was frustrated. My target of choice right now is the good old Crescent Nebula - I've never been happy with my captures of this object - the fine detail in the 'tail' part of the nebula is pretty difficult to get I am finding.

Anyway, cut a long story short, I decided to use the recent data captured with the Televue and the SXVR-H18 combined with the 5 minute and 10 minute subs I had so far with the Vixen VC200L to see how it would look. I decided against registar for this experiment as well - just a simple Sigma Combine in MaximDL using one of the Ha frames from the Vixen as reference to give the Field of View.

I did spend the night capturing as many Ha and Oiii subs with the Vixen though - Managed 5 hours in the end last night (and yes, I am tired now - didn't get to bed until 3.30!!)

Anyway - I am alot happier with this result - the 'tail' is really starting to show - still not completely happy though - I think I am going to have to refine the polar alignment still further and up the sub length to 15 or 20 minutes to really get down to the 'nitty-gritty' - the question in my mind is whether thats a this year or next year project though!

Processing wise, this was quite simple - just threw all the subs into MaximDL, set the FWHM to cutoff at 2, set the roundness to 0.25, and ended up with total capture figures like this:

Exposure (Sii): 245 minutes (490 second average frame)

Exposure (Ha): 240 minutes (411 second average frame)

Exposure (Oiii): 195 minutes (468 second average frame)

Here is the image - theres a full-sized image on my website, click the pic for the big one.

Looking again this morning, the stars are all very reddy in colour - really need to figure out how to fix that.... I set the black point for the image to RGB 20,20,20, so in theory it should have balanced the star colour....

I think its getting there... What do you think?

Cheers,

Richie

[Les Tilly]

Not sure whats going on here looks like it did not combine very well how does each channel look ? I would process each Filter HA,OIII,SII and combine it in Photoshop Star color is going to be off as its a narrowband image unless you added RGB for the stars I always have a Magenta tint when I do it and normally only see it the next day.

Still a great image and plenty of time spent on it

Les

[RichieJarvis]

Thanks Les...

For the Ha and Oiii, there was good data from the Vixen - I am yet to shoot the Sii through the Vixen, so...

Of course! That'll be it (sorry - thinking whilst typing - always a bad idea ) The Sii data will have larger stars as it was shot through the Televue only - the Ha and Oiii both had a good mix from both scopes

I'll just have to shoot a ton of Sii data through the Vixen now, won't I

Cheers - thanks for making me think about it!

Richie