[naskies (Dave)]

Originally Posted by RobF

Extreme imaging for sure Dave. Are you sure you were never into skateboards!
My first thought was that might have been the ESO image actually. Fanastic galaxy detail and the faint galaxies in the background a great. Might be worth doing some shorter exposures for the stars next time, but really, what a stunner!
I've got to get back to my M31. Having lots of gradient problems, probably because it started each night in the T'wba sky glow.

Thanks Rob! It was an all-round great weekend out there. I'm glad we had a day to catch up too.

Originally Posted by strongmanmike

32hrs huh...? Did you have to rotate a dome?

Very nice result Dave, that galaxy chain looks so cool and the colours in the galaxy look good with the HII regions showing nicely, I discarded this galaxy from my possible targets as boring so I'm glad you didn't I can't help but think there might be more in that mega data to surface though I would expect more myself anyway ...but then what would I know it's probably just a monitor thing

Great job

Mike

No dome to rotate, but I had to huff and puff a lot to keep the clouds away I like hunting for the neglected ugly ducklings of the sky... I'm like the fishermen in the background of the John West commercials who pick up the ones that he rejects

Thanks Mike! The 10 hours of Ha don't really count, and 22 hours in my piddly 8 inch scope is like 10 hours on yours, and by the time we compare relative sensitivities of our respective chips, I've really only got about same signal-to-noise as one of your efforts

Yep, I agree that there's plenty of more to dig out of this one. I need to learn more processing skills, as I've primarily focused on good data capture this year. I suspect a lot of Sidionio-ing in my future

Originally Posted by ericwbenson

Hi Dave,
Do you know why the bright stars have a magenta and/or blue flare in the 5 o'clock position? Does your scope have field corrector installed?

The detail in the main object came out really well but I think the colour balance of the brighter stars is off, far too much orange. Perhaps due to trying to incorporate Ha, have you tried just RGB or LRGB to compare?

From a dark sky site the advantage of Ha on broad band sources (e.g. galaxies) is marginal, yes there are emission nebula in there but they are compact plus relatively bright, and the R filter can usually do a good job of isolating them. On galaxies with faint emission jets (M82 being the best example) the Ha can help out.

You mentioned binning 2x2, was that also the case in L? I think for the 8300 sensor it would be better to image L at 1x1 with subs long enough to overcome read noise. The CCD dynamic range is usually more compromised when binning due to the limited well depth of the read out register. I don't know what the hit is in 2x2 for an 8300, you could measure it by looking at the ADU count where a star flattop's.

Best,
EB

Eric, thanks for your tips - very much appreciated The colour flaring is from a combination of factors. I took equal length subs for RGB, but the combine ratio using eXcalibrator was 0.76 : 0.78 : 1.00 and I think the R subs bloomed a bit more in camera. The saturation boost really messed it up.

Yes, I binned the L in 2x2 as well - but in retrospect that wasn't a good idea. It has an especially shallow horizontal shift register that causes weird blooming patterns, which probably didn't help with the colour combine.

The Ha data was actually from my back yard and not dark skies, which is fairly easy/cheap to gather as I have the scope set up semi-permanently there.

I usually aim for sky limited exposure lengths, but it's hard to judge without regularly shooting LRGB regularly. My blue channel was spot on Starizona's ideal exposure calculator at 2x2 binning and 30 mins each, but the red only needed a bit over 20 mins. I overshot the luminance by a fair bit (20 mins instead of an ideal 14) which might explain some of the star bloat too.

There's still a lot to learn... and the more I learn, the more I realise there's yet even more that I don't know

Originally Posted by TimberLand

Very cool, great colours. I'm also a fan of galaxy groups and chains, you have got yourself a keeper there. Mag 24 impressive.

Thanks Justin!