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M97 – The Owl Nebula in Ursa Major

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#1 jgraham



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Posted 17 March 2017 - 03:47 PM

Telescope: Meade 10” LX200 SCT (Wide Field) @ f/6.3, Orion Atlas EQ-G
Camera: Full-spectrum Modified Canon 600D (Rebel T3i)
Filter: Orion Imaging Skyglow Filter
Guide scope: Astro-Tech 60mm, Meade DSI Pro II, PHD
Exposure: 38x120sec, ISO 1600 saved as RAW (Dithered every 4 images)
Darks: Internal (Long Exposure Noise Reduction On)
Flat: 32x5sec, ISO 1600, LED tracing tablet, plus a synthetic flat
Average Light Pollution: Red zone, poor transparency, passing high clouds
Lensed Sky Quality Meter: 18.5 mag/arc-sec^2
White Balance: Nebulosity Automatic
Software: Backyard EOS, Deep Sky Stacker, Nebulosity, Photoshop


I was very surprised at how well this image turned out. After a very clear day, the evening turned cold with high relative humidity and a veil of high altitude haze flowing overhead. I lost about half of the source images to very poor sky conditions. One challenge of these conditions is that the source frames can be uneven; giving an odd gradient that cannot be corrected with a simple flat. To remove the residual gradient I used an old method of creating a synthetic flat. Briefly, you carefully delete the stars and object, filling them in with the nearby background, and then using a median filter to smooth things out, closely matching the average background gradient. Applying this as a flat usually evens everything out quite nicely.


This was the first test image taken with my ‘new’ 10” f/6.3 LX200. Since my first 10” f/6.3 (from LX200 GPS production) is configured specifically for imaging, I was planning one configuring this one for visual and electronic assisted astronomy, but I couldn’t resist at least giving it a test run with my DSLR on it, and I am delighted with how well it performed, particularly given the challenging conditions. If you look closely, you can see that the background is peppered with little background galaxies.


M97 (3-16-2017)-2j.jpg


  • Doug Neal, cmahar, mikewayne3 and 4 others like this

#2 petert913


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Posted 17 March 2017 - 04:32 PM

That's very nice.  I love the subtle red tinge around the blue planetary.   Your scope and gear did good !

#3 TeamHawkins


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Posted 20 March 2017 - 10:25 AM

Looks familiar! lol  Great job.

#4 cmahar



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Posted 30 March 2017 - 05:08 PM

Thank you for the image, and especially for the details of how you captured and processed it.  This is my astro-imaging college, right here on this forum.

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