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tooth_dr

NGC 4631 LRGB (The Whale Galaxy)

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Despite no longer having astro darkness, I want to get some colour on the Whale Galaxy.  Four nights ago it was clear, with a bit of moon, so was able to get 2.5 hours of data during the darkest part of the night.

Luminance = 4th and 5th May / 3 hours

RGB = 11th May / 50 minutes per RGB filter

Total integration time = 5.5 hours in 150s subs at -20oC Atik 383L+ through a SW 250px on EQ6, guided by finder guider / ASI 120MM

 

It doesnt stand up to much scrutiny, and is mushy at close inspection.  My guiding was around RMS 0.8-1" and my imaging scale is 0.92".

 

Thanks for looking, comments welcomed.

Adam

Whale-LRGB.jpg

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I think that is nice Dr and the star look round, I have never seen this before and it really does look like a whale, unlike the Wild Duck Cluster, can never see where they got that from.

Alan

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Nice image. A cracking visual target too. 

Paul

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On ‎15‎/‎05‎/‎2019 at 23:11, tooth_dr said:

Despite no longer having astro darkness, I want to get some colour on the Whale Galaxy.  Four nights ago it was clear, with a bit of moon, so was able to get 2.5 hours of data during the darkest part of the night.

Luminance = 4th and 5th May / 3 hours

RGB = 11th May / 50 minutes per RGB filter

Total integration time = 5.5 hours in 150s subs at -20oC Atik 383L+ through a SW 250px on EQ6, guided by finder guider / ASI 120MM

 

It doesnt stand up to much scrutiny, and is mushy at close inspection.  My guiding was around RMS 0.8-1" and my imaging scale is 0.92".

 

Thanks for looking, comments welcomed.

Adam

Whale-LRGB.jpg

Well Adam, I think it's fair to say the belt mod has been a resounding success! Didn't you say before that your typical guiding pre-mod was usually around 1.5" (and that was with the 80ED?!), whereas this was much lower but with a much bigger, heavier scope, so it looks like a job well done!

Not sure about the mushiness you refer to, I just see a great image. I'd be stoked with that. The only area I would experiment with would be sharpening. You've got shed loads of high-res, high-contrast details in the galaxy. This is also the highest-signal area of the image, so it could definitely take more sharpening to bring it out a bit more. Be careful not to overdo it though, and you only want to sharpen this area alone, and nothing else.

Of course, how much sharpening to apply is very much a personal choice. So if you don't like what it adds then by all means leave it well alone, as it' already a cracking image 👍

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Posted (edited)
13 hours ago, Xiga said:

Well Adam, I think it's fair to say the belt mod has been a resounding success! Didn't you say before that your typical guiding pre-mod was usually around 1.5" (and that was with the 80ED?!), whereas this was much lower but with a much bigger, heavier scope, so it looks like a job well done!

Not sure about the mushiness you refer to, I just see a great image. I'd be stoked with that. The only area I would experiment with would be sharpening. You've got shed loads of high-res, high-contrast details in the galaxy. This is also the highest-signal area of the image, so it could definitely take more sharpening to bring it out a bit more. Be careful not to overdo it though, and you only want to sharpen this area alone, and nothing else.

Of course, how much sharpening to apply is very much a personal choice. So if you don't like what it adds then by all means leave it well alone, as it' already a cracking image 👍

Thanks Ciaran.  The peak to peak guiding was around 4" using my ED80s before the mod, and with that 10" scope it was 2", with RMS just under 1".

I had to run the guiding at 0.5s which goes against the grain.  But at anything more than that the graph was see-sawing between +2 and -2.  I'm not sure what this means but I would like to get to the bottom of it.  It could be a weight issue, or belt mod issue, or flexing issue, I dont know!  If I have to guide at that and I get consistent results then thats ok, but it does make finding guidestars a bit more limited, and I'd say with an OAG impossible.

Edited by tooth_dr

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