Lagoon and Trifid from High Halden

[MarkS]

I took this on 26th June.  I was hoping to make a mosaic but this won't happen now because it's getting too late in the year and I am having an operation on my hand this week which will put me out of action for a while.  So here it is:

Modified Canon 350D on Tak Epsilon ED180 with CLS filter.
18 x 5min @ISO 800 + 5 x 2.5min @ISO 400



Larger version here:
http://www.markshelley.co.uk/Astronomy/2011/lagoon26062011.jpg

It has come out much better than last year's version (http://www.markshelley.co.uk/Astronomy/2010/trifid_2010.html) - mainly because the sky background was much darker at HH than at Beachy Head.

Mark

[JohnP]

Mark - superb once again - even more so considering the relatively few number of subs. Love the colours & the 'misty' feel to it..

Great,  John

[mickw]

Very nice.

Were the shorter, slower subs to save the core ?

[MarkS]

Were the shorter, slower subs to save the core ?

Yes.  The burnt out core is one of the (many) disappointing things about last year's version.

[PhilB]

Very well done

[Mike]

Looks great Mark.

[RobertM]

A great result Mark.  It needs a lot more subs to get some detail in the Lagoon Nebula so I hope you get to do those at some point.

Robert

[MarkS]

It needs a lot more subs to get some detail in the Lagoon Nebula so I hope you get to do those at some point.

Extracting detail in the Lagoon is not that easy.  Being so low above the horizon, the light is passing through at least 4 times as much atmosphere as an image taken at zenith - this means that the seeing creates 4 times as much blurring.

The bigger problem I noticed was atmospheric dispersion which "smears" the star colours giving a red fringe one side of the star and a blue fringe the other.  The real problem here was that the amount of smearing changed from sub to sub over the 2 hour acquisition as the height above the horizon and the angle of the target (relative to the ground) changed.

The only way I could process this image was to completely abandon my usual "full-colour stacking" approach and, instead, split up the R,G,B channels and do a full stack on each channel before recombining later into a colour image.  I still have some blue fringing on the stars in the Lagoon - I'm don't know why but at least it is symmetric!

Mark

[RobertM]

Well, however you processed it, that was a great result from these latitudes !

[Carole]

Oooow, very nice Mark.  (Finally found an internet cafe in northern Majorca ) and this is the first post I´ve seen.  Looks excellent to me Mark.

Carole

[Fay]

Come out very well Mark!!!!!!!!

[MarkS]

Sitting here with one arm I've done a complete re-process.  Subtle difference but I'm far happier with the result.



Larger version (2/3 scaled from full size):
http://www.markshelley.co.uk/Astronomy/2011/lagoon26062011v3.jpg

Mark

[Fay]

yes, like that Mark, more definition & contrast

[PhilB]

Spent a while jumping from one version to the other. The contrast increase has certainly made the detail in the image easier to see. Nice reprocess!

[mickw]

Looks much better.

Nice work lefty