[Added repro version. Thanks for advice from all, especially Greg Bradley!]
Last new moon was the first time with my RC10 under dark skies, so I had a go at a couple of galaxies for a change (up until now I've been imaging at 530mm and mainly targeting nebulae).
Here's my first attempt at processing 7 hours of data for NGC 6744.
Scope: GSO RC10 @ f/8, 2000mm FL
Mount: AP900
Camera: Starlight Xpress H-18 mono
Filters: Astrodon E series Gen 2
Guiding: SX AO-LF and Lodestar
Focuser: Atlas
Image scale: 0.56 arcsec/pixel - a bit small, perhaps
Exposures: 24x10m L, 12x5m R, 12x5m G, 12x5m B
I've never imaged a galaxy before at this scale, so I'd really appreciate any helpful comments on things that would improve the image. I'm planning to reprocess it, but still deciding what aspects of the image I'd like to fix.
BTW, the little galaxy at the top left is NGC 6744A.
Thanks,
Rick.
Last edited by RickS; 27-05-2012 at 04:05 PM.
Reason: Added another repro.
A nice image Rick and a great shot for a first image of a galaxy. NGC6744 is a bit of a toughy and is quite faint.
Its also hard to get a nice colour balance with this one compared to other targets.
So a couple of pointers;
Firstly star sizes seem a little large. Did you use deconvolution on the luminance?
Also see Ken Crawford's tutorial on multiple deconvolution. It can extract more detail which is the name of the game in galaxies.
3rdly the galaxy is bluish with a yellowish core. Your galaxy looks a little grey. Also stars are lacking in colour. So colour can be boosted here.
Selective colour tool is good for boosting individual colours and shades.
Also see free Photoshop plug ins from Neil Fleming for boosing colour saturation and dust in galaxy images.
Nice work, Rick. Glad to see you have your mono camera working properly How do you find the GSO RC10?
It looks like you may have plenty of head room to boost the contrast over the background star field (i.e. curves adjustment). I think there may be a slight blue/green colour cast?
That's a really nice job you've done, it looks natural , great colour and heaps of detail.
I'd hang that on on the wall !!
Cheers,
Justin.
Thanks, Justin.
Quote:
Originally Posted by strongmanmike
Very nice image of this beautiful galaxy!
Mike
Very kind of you, Mike.
Quote:
Originally Posted by ozstronomer
Nice image Rick, looks like you had a good imaging run. Well Done
Thanks, Geoff. It was nice to have two days of dark skies,and especially good not to have to set up again on the second night!
Quote:
Originally Posted by gregbradley
A nice image Rick and a great shot for a first image of a galaxy. NGC6744 is a bit of a toughy and is quite faint.
Its also hard to get a nice colour balance with this one compared to other targets.
So a couple of pointers;
Firstly star sizes seem a little large. Did you use deconvolution on the luminance?
Also see Ken Crawford's tutorial on multiple deconvolution. It can extract more detail which is the name of the game in galaxies.
3rdly the galaxy is bluish with a yellowish core. Your galaxy looks a little grey. Also stars are lacking in colour. So colour can be boosted here.
Selective colour tool is good for boosting individual colours and shades.
Also see free Photoshop plug ins from Neil Fleming for boosing colour saturation and dust in galaxy images.
Cheers,
Greg.
Thanks, Greg. I didn't do a deconvolution. My previous attempts haven't been that successful, but I think it's time to get serious and get out the whip and chair
I used a PI shortcut for colour calibration and it looks like it didn't work this time. I also tried my usual G2V calibrated extinction factors and that didn't look quite right either. Perhaps I just need to tweak the colours to look like other images of 6744?
Thanks very much for the pointers.
Quote:
Originally Posted by naskies
Nice work, Rick. Glad to see you have your mono camera working properly How do you find the GSO RC10?
It looks like you may have plenty of head room to boost the contrast over the background star field (i.e. curves adjustment). I think there may be a slight blue/green colour cast?
Thanks, Dave. I actually had a different problem with the camera. The cooling was a bit flaky. Fortunately, dithering and stacking got rid of the additional noise. I also found out what was causing the previous dust problem. The shutter coating used on early versions of the H-18 falls off.
I'm quite pleased with the RC10 so far. For the price it's hard to beat. It takes some time to sort out imaging at 2000mm but I think I'm getting the hang of it.
From Glen Aplin no doubt? Testamony to the dark skies, as I've only ever had any success with this from Wiruna. Even from Peter's it was tough, but there was smoke in the air that night/year as I recall.
I was a bit surprised at stars. Very round, so tracking spot on. Is is possible focus was a smidge off, or cumulative seeing effect perhaps at such small arcsec/pixel?
Regardless, one of the better 6744s you'd find on IIS I'd wager, especially with a big of colour tweaking (again, agree colour quite tough to get right - Marcus did a great one here a year or so ago from memory might be worth peeking at.
That's one dim galaxy Rick. I had a bash at it last year and had to bin everything x2 to see it with the RC8 so you've done well here.
The dark skies at Glen Aplin certainly helped, Robin, as Rob suggested. Thanks, mate!
Quote:
Originally Posted by [1ponders]
Nice shootin' Rick.
Thank you, Paul.
Quote:
Originally Posted by RobF
From Glen Aplin no doubt? Testamony to the dark skies, as I've only ever had any success with this from Wiruna. Even from Peter's it was tough, but there was smoke in the air that night/year as I recall.
I was a bit surprised at stars. Very round, so tracking spot on. Is is possible focus was a smidge off, or cumulative seeing effect perhaps at such small arcsec/pixel?
Regardless, one of the better 6744s you'd find on IIS I'd wager, especially with a big of colour tweaking (again, agree colour quite tough to get right - Marcus did a great one here a year or so ago from memory might be worth peeking at.
Rob, the AO does a good job of tracking if you get a decent guide star. I was running it at 3-4Hz most of the night. I was refocusing with FocusMax about every hour as the temperature was dropping quite quickly. The seeing was OK but not fantastic, especially on the Friday night. The other factor is my collimation which I think is not bad, but may not be perfect.
Thanks for your comments. I'm going to miss the next new moon weekend as I'll be on a plane somewhere over the Pacific, so I have a couple of months to spend honing my processing skills on the Glen Aplin data! I also have 7 hours on NGC 4038/4039 that shows some promise...
I agree, Top Job so far Rick, I tried this faint Gal but gave up on it, Lol, seeing was a bit below par, Great to see what potential it has ? Great show ! !
I spent a few hours last night reading up on the PixInsight tools for estimating PSF and deconvolution. By midnight I had managed to run my first deconvolution that didn't make the image look worse, so that's definitely an improvement on previous attempts.
I think they're treating deconvolution as a bit of a deprecated sharpening method in PI. They're recommending the multiscale processing process ATWT and more recently MMT. Maybe try these:
![[1ponders]'s Avatar](../vbiis/customavatars/avatar45_9.gif){kind=avatar}
