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Galaxy attempt...


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Hi all

Had my first go at imaging a galaxy this last week. Unfortunately, I'm not spoilt for choice as I'm limited to the eastern sky and there's not a lot about at the moment. Add to that the LP and general lack of darkness then I'm up against it. Anyway, did this over several nights - it's supposed to be Stephan's Quintet in the centre and NGC7331 on the left. I've managed to acquire a total of 102mins integration time, made up from 4x120s, 4x360s, 5x480s, and 3x600s. Now both objects are quite faint, so I knew they'd be difficult to capture but thought I'd have a go. (scope = 150pds with mpcc and IDAS D1 lp filter. Camera was the qhy8l plus qhy5l-ii finder guider)

Anyway, result below, stacked in DSS together with flats, bias and dark frames. Processed in StarTools with some tweaks in CS2. I'm not totally displeased with the result but I'm wondering whether the image is likely to improve with more integration time or do I really need longer subs? (as well?). Not that I can do longer subs - I'm rather limited to 600s because of the city lp. I guess contrast would be greater if the skies were darker... Weather forecast not good for this week :( so looks like this will have to remain a work in progress for now.

M31 is coming round so hope I get an opportunity to image that :p

Thanks

Louise

post-33532-0-77928700-1403635726_thumb.j

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There are quite a few faint fizzies in the capture and this is no easy target, very well done.

A.G

Hiya

Thanks :) Stephan's Quintet is in the centre, albeit faintly! I hope to get some more data tonight - fingers crossed! Wish I had more fl though...

Cheers

Louise

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Stick to your longer subs and grab as many as you can. Stephan's quintet is a very tiny grouping, so don't expect too much with a short FL scope, it's small in my 12 inch scope at F8. NGC7331 is a good target though and should come through well.

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Hi Rob

Yeah, I think I was a bit over-optimistic about imaging these though I knew they'd appear small! I've tried adding another hour's worth (5 x 480s, 2 x 600s) but not much difference, even without the shorter subs included. Unfortunately 600s is a max exposure here because of the lp and sometimes even they come out too bright to use :(. Sigh. More fl would certainly help too. Oh for darker skies...

Oh well, I'm going to have a go at M31 soon - if the clouds stay away! :)

Thanks for the input

Louise

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How are you combining the different exposure lengths? My feeling is that each exposure length should be stacked independently and combined afterwards otherwise differing pixel values between each set will cause excessive pixel rejection by the stacking routine.

Andrew

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It is a great pic. I love viewing this area of the sky with my dob and your image picks up the objects I can just see in my 14 inch visually.

You have picked up the brighter galaxies around NGC 7331..

Thanks for sharing.

Mark

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How are you combining the different exposure lengths? My feeling is that each exposure length should be stacked independently and combined afterwards otherwise differing pixel values between each set will cause excessive pixel rejection by the stacking routine.

Andrew

Hi

I've been stacking in DSS using separate file groups and the entropy weighted algorithm. I've since been collecting more 480s subs - hope to get some more tonight :)

Cheers

Louise

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It is a great pic. I love viewing this area of the sky with my dob and your image picks up the objects I can just see in my 14 inch visually.

You have picked up the brighter galaxies around NGC 7331..

Thanks for sharing.

Mark

Hi thanks. The objects are a bit small for my fl but nothing much else in the east at the mo.

Cheers

Louise

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Hi

I think you could be rather more aggressive with the non-linear stretch. It looks rather dark on my monitor and you've got enough exposure to keep the noise under control.

Andrew

Hi

Maybe. I have 5 or 6 x 480s to add to the data plus whatever I might get tonight - fingers crossed! Then I'll have another go with the extra data.

Cheers

Louise

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That's a fantastic photo, got me wondering if Stephan's Quintet is a visual object for me . hmmm

Hi

Well it's mag 13.6 so is very faint in my wee 150pds... But maybe visible in a big Dob! NGC 7331 / C30 should be easily visible.

Cheers

Louise

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Hi

Indeed, I'll have a look at it, it's high on my to view list now :)

Hi

I'm just taking advantage of the rare, clear, light-polluted, Glasgow skies and grabbing some more subs :) There's nothing like imaging, y'know! :)

Louise

Edit: hmm... not so clear as I'd like, but I'll keep going

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Hope you had a clear night, I know Glasgow well, I stayed near Lesmahagow, on Brockets Brae for 6  months in 2010, nice dark skies, Glasgow was visible from the back of the house :)

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Hope you had a clear night, I know Glasgow well, I stayed near Lesmahagow, on Brockets Brae for 6  months in 2010, nice dark skies, Glasgow was visible from the back of the house :)

Hi

Unfortunately the atmosphere was murky and guiding was rubbish. I took some subs but not sure how many are usable - will have a look tomorrow. I live close to the city centre - it never gets dark here... :-|

Cheers

Louise

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