Dusty Jewels of the Southern Crown QHY8

[Astrod00d]

NGC6726 and surrounds in Corona Australis. Imaged in the early hours of Saturday morning, just before moonrise, using a borrowed Zenithstar 105. This region fascinates, but has eluded me in the past, the dust clouds are normally lost in skyglow.
The blue nebulosity around the central stars quickly fades to clouds of dust, visible as brown columns against a dark sky background. The globular cluster balances the image nicely.

I'm still learning to use the QHY8, this time around I've reduced the gain and gone for longer subs. This appears to work, the lower gain results in better dynamic range. I'd like to spend more time imaging this region, on a clear night 120 minutes or more (8x900s) should bring out more detail in the dust clouds.

Mount: EQ6
Guider: ST80, webcam, GuideDog
Imager: WO Zenithstar 105, QHY8 at prime focus
2 x 900s, 2x600s, 1x300s median stacked using DSS, no darks.
Levels, curves Photoshop.
Captured using Nebulosity, Gain 20 (31%), offset 116.

Cheers,

Rob

[Lester]

Very nice image Rob.

[Hagar]

Very nice image Rob. The area is one I have not spent any time looking at. I have been staying with the better known areas while I learn about my QHY8.. A very sensitive camera which requires some work and experimentation to get it right.

Good stuff, show us some more!!

[jase]

Nice Rob, nice. As you indicate, this is a fascinating area of the night sky. The dust cloud extends a considerable distance. Processing looks pretty good. Surprised you didn't take any darks. Perhaps this is contributing to the dark spots around the image, though I would expect that to be more likely flats. I wouldn't bother combining subs of different exposures unless your using a HDR process. You're better off taking 5 x 10 min subs instead of 10 x 5min subs. Longer subs will give you a more pleasing result, unless of course you need to handle the object's vast dynamic range or your using a NABG chip prone to blooming. Combine the data with same exposure time subs. Then layer the two in PS. There are plenty of other ways to handle the dynamic range situation. Overall, well done. Look forward to seeing more as you start tuning the camera.

[Alchemy]

very nice :thumbsup:

[monoxide]

nice work Rob

[h0ughy]

nice image, the dust shows up very well

[Peter Ward]

Indeed! ;)

This is a tough object Rob (at least from the 'burbs). Handled well. :thumbsup:

But you need to seriously look at doing flats darks etc. They really are an essential part of digital imaging.

Cheers
Peter

[Gama]

Nice, your on you way up from here.

Theo.

[Zuts]

Hi,

Lovely shot. This is one of my favourite areas, the blues and browns make it a very interesting part of the sky. I also tried this from the burbs but got a shot I was happier with from dark sky.

looks great to me

Paul

[Garyh]

Not bad Rob! :thumbsup:
I love this area of the sky!
cheers

[Astrod00d]

Thank you all for your kind comments! Especially the advice which is always well received.

The shot was taken from the lower Blue Mountains, so not exactly the 'burbs, but not a pristine dark sky site either.

The mixture of exposure times is my fault... I started out with a modest 300s, and kept increasing the time as each sub came in well below saturation. If the moon hadn't risen, I would have shot many more 900s subs and used those in my stack. I'll re-process again this evening using only the two 900s subs and see how it turns out.
The dark spots in the image are residue on the ccd glass and should clean up once I add flats. Haven't had the chance to take flats with the Zenithstar 105 just yet, another thing for the to-do list ;). One note, DSS seems to over-compensate flats. (The dark spots become bright spots) Perhaps it's just a setting I haven't tweaked properly yet.

Not sure about darks with the QHY8. Sometimes I get a subtle moire-like effect when I use DSS to apply darks to my QHY8 images. I'll try generating a bad pixel map and do some pre-processing using Nebulosity, there are a lot of functions in Nebulosity that I haven't tried just yet.

So much to learn! This is fun!

Cheers,

Rob

[seeker372011]

rob

thats a great shot

its certainly worth taking darks ...,the bad pixel map routine works a treat with the Qhy8

IMHO you just dont need to take as many darks as you do with a DSLR..you can get away with far fewer so its not as painful wasting the precious night taking darks

BTW I notice people on Cloudy Nights generally are shooting with gain at 1!

I havent tried it that setting..I have been more at the setting you have used
but lovely shot!
Narayan

[skeltz]

Good one rob ,the glob the nebulas and the dark dust lanes make a very pleasing image1