M37 and 38, December 06-07

[darditti]

Here are the other two added to M36 to complete my trio of Auriga clusters recorded on this night in first quarter moonlight.

This was a first test of the imaging system consisting of QHY8, Baader MPCC and Lumicon Newtonian OAG. I have put a post showing how this setup is arranged on the "Imaging tips & techniques" board http://stargazerslounge.com/index.php/topic,35858.0.html

Very pleased with these. These pictures at 25% are linked to pics at 50% size, but even at 100% is is hard to see coma except in the corners. It's also an interesting comparison of these clusters at more or less the same exposure and conditions.

David

(Click to enlarge)

(Click to enlarge)

(Click to enlarge)

[RobH]

Nicely done trio David

Cheers

Rob

[Talitha]

You should be very pleased David, they're lovely.. thank you!

[barkis]

Yes, great images of three lovely clusters. Clusters do it for me, whether open or Globular.

I used to enjoy Society Slide nights when they we projected on to a large screen in the darkened room.

Great stuff David.

Ron.

[thing]

My three favourite clusters, nicely done David.

[ollypenrice]

Chapeau, David. Crisp. clean stars on a dark background from an urban observatory. I have no idea how you do it but I'm glad you do. Lovely images.

I'm chomping at the bit down here and digging the observatories out of the snow in readiness for some clear winter skies next week, as promised by the weathermen.

Olly.

[darditti]

I have no idea how you do it but I'm glad you do.

Well, a lot of it is software. GradientXterminator does a very good job of not only exterminating gradients (which were actually not too much of an issue here as the subs were short) but of balancing the background to neutral, so removing the urban orange skyglow. I used to think it was not possible to take good colour starfield pictures from here, only filtered ones, because of the skyglow, but the software means it is. GradientXterminator does not do anything that could not be done in Photoshop or similar programs on their own, but it does make it far easier.

David

[hellibird]

Yes, great images of three lovely clusters. Clusters do it for me, whether open or Globular.

I used to enjoy Society Slide nights when they we projected on to a large screen in the darkened room.

Great stuff David.

Ron.

We have projector, screen and darkened room.

Let's show these lovely images BIG at next week's Astronomers' Forum!

(PM darditti or me for details; there will be mince pies...)

[661-pete]

Very nice one David - since I'm more of a 'globular' person myself (as you know!) I'd choose M37 as my favourite of the three, seeing as it's got the most stars (and it's the most mature, with lots of lovely red giants showing through). But all three are worth a long lingering look.

How does GradientXterminator work? Does it pull on the curves alone or is it something more subtle? For cleaning up the muck behind a cluster with LP, if there's no nebulosity to preserve, I'd tend to use sky subtraction by layers (which I learnt how to do, off one of the forums. That's the value of forums!)

Doubt if I'll be able to make it to your next weeks event, sorry! Too much to do. Next year hopefully!

[Mel]

These rank in my top ten favourite visual objects and are defo in my top 5 fave clusters, and you've captured them beautifully. Nice one

Iain

[Doc]

They are all excellent.

Well done.

[darditti]

How does GradientXterminator work?

All I know is what it says in the rather brief on-line manual:[br][br]"GradientXTerminator works by using the selected portions of an image to estimate the background gradients. A mathematical model known as a "thin-plate spline" is constructed based on these portions of the image. Think of this process as bending a "rubber sheet" so that it follows the brightness gradients in the background, but not the brightness of the objects in the image. This model allows the plug-in to estimate the pixel values of the background gradient in the unselected portions of the image, including parts of the image with brighter foreground objects such as galaxies, nebulas, and star clusters."[br][br]David