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NGC5146 + 1 Hour


centroid

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Following on from my previous 'thread' (NGC4146 the Cocoon), I Managed last night, to get another hour's worth of 600 sec subs, before drifting cloud stopped play.

I have now combined these with the previous nights subs, to produce a two hour exposure version of the original one hour image.

It certainly has enhanced the image, but I still believe my H9C is lacking in sensitivty, as I'm convinced the original one hour image should have been better.

So, here's the two images for comparison. The original one hour version, and the new combined two hour version.

Both now correctly labelled as IC5146, and not NGC5416 :D

BTW, yes I realise that I forgot to 'shrink' the stars a bit in the new version :D

Dave

P.S. a light and meium 'median smoothed' versions now added.

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Hi Dave, assuming that you have processed this second image the same way as the first, it has certainly made a huge difference to the saturation and smoothness being able to combine both sessions.

I wish I could think of an empirical method of comparing your CCD with mine to help you determine if there is a problem or not - keep us posted.

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Hi Steve, yes both images processed in exactly the same manner.

I've just added 'smoothed' versions for comparison puposes, both with a Median filter, applied at two slightly different levels.

If we lived a bit closer together Steve, comparing the two cameras would be easy, as we could a comaprison on the same object, with the same scope, on the same night.

Dave

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well those extra subs have made all the difference there Dave , so much smoother ,and pretty deep as well , getting the outer fringes , so what makes you think the ccd is not up to Par then , i would have thought at least 20 subs really with that camera for a noise free image anyway. thats at 10 mins,

but i,m no expert on colour anyway .lol

Rog

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so what makes you think the ccd is not up to Par then ,

Its just a 'gut feeling' I've had since first getting the H9C, and thinking back to when I was using the lesser MX7C, on a 10" scope, not a 12".

I could be completely wrong of course, but without at least another 285 'chipped' OSC camera to compare it with, I can't prove it, one way or the other.

Dave

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Maybe at kelling you could get together with another H9C Dave?

Either way, its a beauty of an image, lovely form and shape to that nebula. The extra hour has made a huge difference.

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Kelling is still not a certainty, as its yet to be decided whether or not we are off the Australia, in October or November.

If its October, then I'll not be able to make Kelling.

However, if I do get there, then your suggestion is ideal.

Cheers

Dave

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That extra hour has made a huge difference Dave....a much smoother image now.

I reckon on trying to get at least 2 hours on an image, irrespective of the sub length (circumstances permitting :D ), that way the noise just dissapears into the backgound

Cheers

Rob

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I think the 2 hour cocoon looks great Dave. How are you determining your exposure time? I've been spending a lot of time thinking about how we can get the most out of our imaging time and one key seems to be ensuring our sub exposure times are optimal. 600 secs sound too long unless you have a nice dark sky.

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How are you determining your exposure time?

I guess its trial and error Martin.

Don't forget that the H9C requires a lot more exposure time than the H9, unless mine is down on sens, as I suspect.

I am fortunate to have a relatively dark sky location, being 6 or seven miles from the nearest town to the north, and 12 miles to the south. As I tend to do all my imaging from the east through south to west, and from the zenith down, the sky glow from Ipswich, to the north isn't a real issue.

It depends on the object, but I feel that to get anything like reasonable subs to 'stack', from a mag 30 object, then 10 minute subs or longer, are needed.

I suppose that given the time, and enough clear sky, I could take something like the cocoon, and say do an hour at 300 or 400 secs, and then an hour with 600 sec subs, and see how the results compare.

Dave

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