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winfij

Sh 2-240 : a seriously faint supernova remnant

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Hi all,

I've not been around much since the xmas break - work's been busy, but I managed to get the scope out for 4 nights over the last week.

I wanted to have a go at imaging Sh 2-240, which is a really faint target. There are a few images on the web, some very good, but not too many in total.

From the outset, I knew it would require a lot of long exposures, but with my main scope out of action I had to use my 75mm aperture scope, imaging unguided. The small aperture meant even more exposures were needed, but with an automated setup it was mainly a case of waiting for good weather.

I was using my 7nm Ha filter, which does a reasonable job of cutting out the moonlight - this was imaged starting just after the full moon, not ideal, but that's when the good weather started.

Even after stacking over 19 hours of subs with the 7nm filter, the nebula was only 15 ADU brighter than the background, so processing was tricky and good calibration essential. I used 100 sky flat field images to give a good correction to allow me to push the processing as much as possible.

Click the image below to see the imaging details and full size image.

Sh2-240-20090118-Ha.jpg

If you're using IE7 and can't view the link above, try this

Hope you like it - constructive criticism welcomed :)

Cheers,

John

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Superb!

and I compliment you on your extreme patience in recording this faint object.

I hope if you submit it to S@N or other Magazine, they publish it, because it deserves to be.

I'm not sure if adding colour is too much of a chore for you, but either way, it is a

very creditable piece of Imaging. Well done John, I don't recall ever seeing this one anywhere.

Ron. :thumbright: :salute:

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Wow! that's taken a lot of dedication and work to capture and process, well done! A stunning image!

Sam

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Hope you like it - constructive criticism welcomed :)

I think you'd have to go some to criticise that image John. I'm aware of how hard that is as an imaging target and any attempt, let alone your one is above criticism. Superb shot :).

Tony..

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This is a superb image and never seen before.

Fantastic processing too.

I thought that I would give it a go but after reading your comments I thought better of it.

Vince

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I've seen this before only once, over at sharplesscatalog.com (http://www.sharplesscatalog.com/sharpless/sh2-240.jpg) This image I link to here is a 12 hours exposure with STL 6303- XE Cam through an Epsilon 160 @F3.3

It's an amazing object; I don't know of anyting else up there that looks like it.

Im amazed by the dedication you have put into the image. It must feel real good to know that you have produced one of very few good images that exists of this thing?! :)

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That is a bit special John. 19 hours!!! Apart from Kelling that's more than I managed the whole of last year.

You have captured all the delicacy of the target. Excellent

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That is awesome. :) :) :)

How long where the individual subs for it?

Mike.

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Top job, lots of lovely filamentary detail in this big object. Now to crack some more of the 'ol Sharpless catalogue.

Cheers

PEter

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That is outstanding - a very difficult widefield object indeed.

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Amazing image - that is some dedication, and very fine control to get everything lined up night after night.

Very impressed.

Cheers,

Richie

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Thanks for all the nice comments all. :)

Ron - I'd absolutely love to get some color data for this, but the clouds are back and it's been raining all afternoon. Maybe it'll clear up a bit next week, but it looks settled in for now.

Mike - this was a stack of 115 x 10min subs, all unguided with my Art11002 through a Pentax SDHF-75

I'll update this thread if the clouds part and allow me to get some RGB before the target moves out of the prime imaging altitude.

Cheers,

John

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