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Cygnus Loop Update (Ha)


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Right, Ive now got the 2nd half of the loop in Ha.... however, ive learnt a few lessons along the way when it comes to doing a mosaic with a 383.

Firstly, 2/3rds focusing - I ended up having to reshoot the Ha for the Broom and Wisp because the stars were dreadful so the difference in star sizes was obvious between the two panes (was originally shot with a centrally focused star). So that was 3 hours worth of subs in the bin! Secondly, I need to leave more of an overlap between panes to take into account any field curvature. My usual methods didnt work, so in the end I turned to Microsoft ICE and it did the task without a grumble. .. not bad for free!

Im hoping Sunday will be clear from sunset onwards, that will give me just enough time to get some OIII in before the Moon rises too high.

Cygnus Loop (Ha)

18x600 (Ha) x2 Panes

80ED (0.85x), Atik 383L+, NEQ6

Setpoint: -20

Thanks for looking! :)

Rob

9577459175_0c3b172dee_b.jpg

Fullsize here: 4154x2969

http://farm6.staticflickr.com/5484/9577459175_2cff4bb0db_o.jpg

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Lovely detail in that :) Just 4 more panes of Ha then 6 each of OIII and SII :D That should produce a truly wonderful image of the Cygnus Loop :)

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Thanks Gina :)

I think I might stick with just the two panes, as this has been a bit of a headache to get right. I've noticed a problem with a few of the stars in this one as theyve picked up some black pixels, it must be a result of using ICE as they are not present in the stacked matsters.

Ive experimented with stitching together a part processed version and the black pixels are now gone, but the background levels between the two panes are different - so its going to take some trial and error to get it right.

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Thanks guys, with a bit of added luck it *might* get completed tomorrow night.

Im also in the middle of negociating with a neighbour about taping off part of the sensor on his security light - just so every time his neighbour goes out for a fag (which seems like every 10 min!) the light will stay off. I'll give it a week or so, and if its not done I will seriously have to think about deploying countermeasures.

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Hi Rob,

That's really tight and clean. Coming on a treat. I know it's easy for me to say because it's you doing it but if you got the bottom extended I'm sure you'd find it worth the effort.

With ICE are you saving a flattened image ? If so you could try saving to a Photoshop image. Once opened in Photoshop it reveals three channels. The bottom one is a flattened and balanced image and the upper two are layers. If you un tick the eye on the bottom one you'll see that you can manipulate either or both channels at will. You can also change the overlap order. This way you can check out and use the best looking stars. Another neat trick is you can smooth the overlap by using the eraser tool. All sorts of processing options open up and you can either save the bottom layer on its own or just delete it.

If you already know all this then ignore :)

Dave.

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Hi Rob,

That's really tight and clean. Coming on a treat. I know it's easy for me to say because it's you doing it but if you got the bottom extended I'm sure you'd find it worth the effort.

With ICE are you saving a flattened image ? If so you could try saving to a Photoshop image. Once opened in Photoshop it reveals three channels. The bottom one is a flattened and balanced image and the upper two are layers. If you un tick the eye on the bottom one you'll see that you can manipulate either or both channels at will. You can also change the overlap order. This way you can check out and use the best looking stars. Another neat trick is you can smooth the overlap by using the eraser tool. All sorts of processing options open up and you can either save the bottom layer on its own or just delete it.

If you already know all this then ignore :)

Dave.

Its all new to me Dave - so thank you very much! :)

I wondered a couple of days ago whether to save it as Ps file, as until now Ive been saving it off as a tiff. Next time Im woking on it I will give it a try.

Sarah, unfortunately no PI here. But Ive found a temporary way round it by part stretching each pane before combining in ICE, though extra care has to go into matching the background levels as best as possible - easier said than done! (wish there were an action for it). It works (just about), but its going to get tricky once I throw in the OIII. Not an ideal situation to be in, so I think I will order some new adapters this week to tinker with the flattener spacing slightly - maybe then I wont have to use ICE anymore and my mosaics will work properly again.... we shall see!

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