NGC253 captured over two nights last weekend at the AAQ Dark Sky Observing weekend at Glen Aplin (props to John Salini for being such a gracious host!)
Inspired by Mike Sidonio's attempts to show the extended halo of NGC 253 I have attempted to do this too. Not sure if the experiment has been entirely successful but you have to try these things. Unfortunately, my FOV is too small to include the Peter Ward S-bend
Wow, high impact image. The image really shows the glow coming off that galaxy and its luminosity.
The red rings around the yellow stars could be minimised a few ways. The best would be to run deconvolution on the red subs to reduce the size of the stars. Perhaps you may need to refocus when doing the red subs or seeing was worse then or the object lower in the sky. Another way is to select an eliptical lasso around the yellow star, feather it 1-2 pixels and lower the red using colour balance tool or selective colour set to red. Then do the next star etc.
This is a great setup you've put together. High quality image.
Nice work Rick. You must be pleased with the Ceravolo.
Chris
Thanks, Chris. It's a very nice scope and I'm pleased I didn't penny pinch ;-)
Quote:
Originally Posted by DavidTrap
Love the star colours Rick! (And the galaxy full stop)
DT
Thanks, David.
Quote:
Originally Posted by gregbradley
Wow, high impact image. The image really shows the glow coming off that galaxy and its luminosity.
The red rings around the yellow stars could be minimised a few ways. The best would be to run deconvolution on the red subs to reduce the size of the stars. Perhaps you may need to refocus when doing the red subs or seeing was worse then or the object lower in the sky. Another way is to select an eliptical lasso around the yellow star, feather it 1-2 pixels and lower the red using colour balance tool or selective colour set to red. Then do the next star etc.
This is a great setup you've put together. High quality image.
Greg.
Thanks very much for the suggestions, Greg. I feel a repro coming on.
Quote:
Originally Posted by RobF
Sure is pretty cool stuff Rick. I'd enjoy it a bit more if the star halos had a bit of erosion to smooth, but heck its already 11/10
Thanks, Rob. I did do a fair amount of work on the stars but bringing up the halo made them bloat again. I think I should have masked them for the final stretch. Hmmm... why didn't I think of that earlier?
That Ceravolo telescope seems to be really sharp.
It is however a Cassegrain & not a Ritchey Chretien so
I am wondering about it's spot sizes off axis in comparison.
Do you have any comparison charts?
Thanks, Allan. The Ceravolo is a Dall-Kirkham design. Peter doesn't publish spot diagrams AFAIK.
Cheers,
Rick.
Yes Rick,
I noticed that when I went to the website.
It all seems quite confusing but your image is so sharp
that I start to wonder about the worth of spot diagrams.
I'm a bit late with this one Rick. A spectacular image to be sure and one of the best images of this galaxy I've seen.
Cheers
Steve
Thanks, Steve!
Quote:
Originally Posted by alpal
Yes Rick,
I noticed that when I went to the website.
It all seems quite confusing but your image is so sharp
that I start to wonder about the worth of spot diagrams.
cheers
Allan
Allan, I've been reading the Telescopes, Eyepieces, Astrographs book by Smith, Ceragioli and Berry. They analyze a lot of designs in detail including Ritchey-Chrétien and Dall-Kirkham. Both need a corrector to cover a wide image circle (RC has field curvature and DK has coma) but with a corrector both designs are capable of very good performance.
The book shows spot diagrams for all the designs they analyse and ray-fan plots are provided as well. These are really useful - you can actually "read" the aberrations from a ray-fan plot and get a much better feel for the (theoretical) performance of a design.
That image jumped out at me so rich and bright, I thought you had used Ha as a few red patches have come out. Only criticism is the bright stars and diff spikes are a bit too dominant but you have brought out the halo very clearly.
Nice going Rick. Heaps of detail and sure is high impact. Agree with what others have already said re the red stars. They seem to have a dark ring on my monitor.
