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Sh 2-240 : a seriously faint supernova remnant


winfij
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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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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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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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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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