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40 minute Sombrero.

ollypenrice

By ollypenrice
in Imaging - Deep Sky

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ollypenrice

ollypenrice

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We don't just do 400 hour images here!  :grin: This is a real quickie to see what happens if you take just one ten minute sub in each of LRG and B. We don't have the right FL for the Sombrero at the moment so this is massively cropped. I used a synthetic Lum derived from the RGB to combine with the real L but, as usual, the 30 minutes of RGB had far less signal than the ten minutes of luminance.

So here's the full forty minute's worth.  :rolleyes:

Sombrero%20in%2040%20minutes.-L.jpg

Olly

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ollypenrice

ollypenrice

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Great pic. A question from someone who doesn't do AP, is how do you get the FL that you require?

The focal length in deep sky imaging is a property of the particular telescope. Planetary imagers can increase a given scope's FL with Barlows or Powermates because they have plenty of light. In deep sky, alas, we cannot do that because such an increase in FL comes at the expense of focal ratio. If we double our focal length this way we quadruple our exposure times and this renders the situation impossible.

At the moment we have focal lengths of 530 and 980mm available here from different refractors. The Sombrero needs at least three metres which means a truly enormous scope and mount, along with excellent seeing because turbulence at long FL is disastrous.

May is a lean time for short focal lengths but a Milky-Way-full of large targets is already aloft by three am so our time is coming!

Olly

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laser_jock99

laser_jock99

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Nice 'wide field' picture.

I dream of a long FL and the mount to go with it. But as you say any kind unsteadiness in the atmosphere would render it pointless (I can quite easily end up with blobby stars at 1200mm). So a nice site on a high mountain is needed to go with it.......  

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MartinB

MartinB

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Looking good Olly but I don't think it's the best target for your experiment given that it's quite a bright target and there isn't much in the way of faint outer zones.  Nice star colour.  Perhaps you should stick a x3 barlow in the TEC!

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BeanerSA

BeanerSA

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The focal length in deep sky imaging is a property of the particular telescope. Planetary imagers can increase a given scope's FL with Barlows or Powermates because they have plenty of light. In deep sky, alas, we cannot do that because such an increase in FL comes at the expense of focal ratio. If we double our focal length this way we quadruple our exposure times and this renders the situation impossible.

At the moment we have focal lengths of 530 and 980mm available here from different refractors. The Sombrero needs at least three metres which means a truly enormous scope and mount, along with excellent seeing because turbulence at long FL is disastrous.

May is a lean time for short focal lengths but a Milky-Way-full of large targets is already aloft by three am so our time is coming!

Olly

Thanks for that explanation.

FL or not that looks nice, would be interesting to see what

the sombrero and field of view you have there would show

with one of you 10 + hour specials Olly

Go on you Know you want to :)

Paul

Paul Haese recently did one with an integration time of about 18 hours, it's pretty cool

http://paulhaese.net/M104.html

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Stargazer33

Stargazer33

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Only four ten minute subs! We dreamed of 10 minute subs as kids. We woz lucky to get the back of our dads hand and that was after gettin' up two hours before we went to bed and doing a 14 hour shift down the pit! :grin: Sorry! Too much Monty Python!

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Davey-T

Davey-T

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Nice representative astro image of what us mere mortals can aspire to. Whilst I have the focal length to capture it I've no chance from my location as it's hiding in the tree tops. If only I lived up a mountain, I'd show it  :grin:

Dave

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ollypenrice

ollypenrice

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Looking good Olly but I don't think it's the best target for your experiment given that it's quite a bright target and there isn't much in the way of faint outer zones.  Nice star colour.  Perhaps you should stick a x3 barlow in the TEC!

You have me, Martin! Had my guests suggested the Owl in double quick time I'd have suggested the Sombrero... It's bright and worth a pop in a quickie.

FL or not that looks nice, would be interesting to see what

the sombrero and field of view you have there would show

with one of you 10 + hour specials Olly

Go on you Know you want to :)

Paul

Honestly the difference would be slight. More data would make it easier to process but, on a bright target which is far too small for the focal length, diminishing returns would set in after a few subs per filter, I reckon.

We all really enoyed the Sombrero in the Dob and catching a memento like this will have to do us. As for choosing a long FL scope, this really is a tough choice and I haven't had the decisiveness to do it so far!

Olly

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NickK

NickK

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You can easily spend hours on the Sombrero.. 40 hours, 40 hours 1/2 pixel to the left, 40 hours 1/2 pixel up,.... Galaxies and Planetaries usually respond really well to drizzle (super resolution).

Lovely target, only issue is that at the SGL star party this is low down in the vapour :( but I always check it to see if it's worth imaging.

Awesome frisby image :D

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