I started collecting data for this galaxy about a month ago. I have in fact collected over 30 hours of data but rejected all but 17.5 hours because of the rotation issue of the image. For some reason some nights at the time of the meridian flip the rotator rotates 3 degrees more than it should. It is not consistent and it presents another bug hunt I need to conduct.
The subs were 30 minutes for the luminance (I learned my lesson from NGC300 where I used 20 minute subs). The colour subs were 20 minutes each. So 510 minutes for Lum and 3 hours each on the colour.
I think I could have done with another 10 hours of Lum data, but I want to change my filters over to the Astrodons I bought. I might consider getting some Ha data though, as this galaxy has a heap of Ha regions.
Nice shot Paul.
What caused the slight diffraction spikes?
cheers
Allan
Hahaha, these diffraction spikes will be the bane of you Paul! Great image! You should just get a fast Newtonian and be done with it, because you end up with the spikes anyway.
Nice shot Paul.
What caused the slight diffraction spikes?
cheers
Allan
Allan, this is a micro lensing issue on the KAF8300. I have heard this from several sources and have to come to accept it. It is on the base images, but is enhanced by processing.
Quote:
Originally Posted by Peter.M
Hahaha, these diffraction spikes will be the bane of you Paul! Great image! You should just get a fast Newtonian and be done with it, because you end up with the spikes anyway.
Hehehe, I don't have any dramas with them. I was brought up with diffraction spikes so it all looks normal to me. I am looking at another wide field set up down the track, but I don't think I will go with a fast Newt. However, never say never.
Paul, that's one of the best 55's I've seen. In your image it looks like a well formed galaxy rather than a misshapened nebula with little detail. The colour really adds to this image and I like it a lot
Allan
Nice. Do you have a larger version, I'd like to do a comparison between your's and mine? How do you get away with 30 minute Luminance subs, doesn't the skyglow limit this? If I did 30 minute subs I reckon I would have a purely white image. You must have really dark skies.
Do you want my Ha data? I did a very quick combine in CCDStack with the luminance data, basically just added the two combined images together, I'm sure there's a better way to go about this. I might try a layering technique over the galaxy and a lighten combine in PS, waddya reckon?
Cheers
Stuart
P.S. please ignore the larger version question, how do you do a strikethrough character in this??
Last edited by rat156; 10-10-2013 at 06:50 PM.
Reason: Should really read the first post better, missed the link...
Paul, that's one of the best 55's I've seen. In your image it looks like a well formed galaxy rather than a misshapened nebula with little detail. The colour really adds to this image and I like it a lot
Allan
Hey thanks Allan, really appreciate that.
Quote:
Originally Posted by rat156
Hi Paul,
Nice. Do you have a larger version, I'd like to do a comparison between your's and mine? How do you get away with 30 minute Luminance subs, doesn't the skyglow limit this? If I did 30 minute subs I reckon I would have a purely white image. You must have really dark skies.
Do you want my Ha data? I did a very quick combine in CCDStack with the luminance data, basically just added the two combined images together, I'm sure there's a better way to go about this. I might try a layering technique over the galaxy and a lighten combine in PS, waddya reckon?
Cheers
Stuart
P.S. please ignore the larger version question, how do you do a strikethrough character in this??
Thanks Stuart, I have my observatory located about 90km from Adelaide. The skies there are very dark. Last weekend I registered 22.06 on my SQM, then another couple of readings at 21.78. 21.96 depending on where I pointed in the sky. That affords me the luxury of 30 minute subs. This year I went fully automated so I can image from home in Adelaide. Such a god send and I get heaps of sleep now as opposed to be before.
I think if you use pixel math in MaximDL you can combine the Lum and Ha data really well. Jase is always talking about doing this. I may just have to try getting some Ha for it. That will have to wait for me to change the Astrodons. Maybe tomorrow. Thanks for the offer of the Ha, I think I will get it myself though. That is very nice of you to offer .
I hope you don't mind, but I stole your image from the larger version and used it with my original as a colour layer, I'll add the images to my thread on NGC 55. I've made a 3 frame video as well to show the difference. I'll drop that on vimeo or youtube. It makes a compelling case for more time spent on the colour for this one for me.
Of course if you do mind, just let me know and I'll remove the images.
I started collecting data for this galaxy about a month ago. I have in fact collected over 30 hours of data but rejected all but 17.5 hours because of the rotation issue of the image.
Paul,
Nice to see a good and deep NGC 55, for a change.
For some reason, people seem to make shallow exposures of this galaxy, perhaps for the reason that these are "good enough" to show the boxy/irregular LMC-like central part of the galaxy (which is of notably high surface brightness.)
The outer zone of very blue structure is interesting.....do I see some poorly-defined spiral arms there? Arguably, if this galaxy were deprojected to a face-on orientation, there is just a hint of spiral arms opening in an anticlockwise direction.
Because NGC55 is so near to edge-on in orientation, it is exceedingly difficult to figure out what it would look like if it were in a face-on orientation.
In general, it could be classified as a Magellanic spiral of type Sm, due perhaps to the merest hint of spiral structure and regularity in its structure (as distinct from a bona fide irregular galaxy). But there is not a lot to go on because of the orientation.
cheers, Robert
One does get the sense of significant regular structure in this galaxy, though rather chaotic and entropic; for instance, there is a rough and ready bulge-like structure of older stars surrounded by an annulus of much younger stars.
Last edited by madbadgalaxyman; 10-10-2013 at 07:35 PM.
Looks great Paul. Nice star colours and hints of pink in the HII regions. the brighter portion has been dodged well and there's so much detail. The background sky looks a little lumpy - not sure if this is faint stars or a bit of noise still, despite the marathon exposure.
I hope you don't mind, but I stole your image from the larger version and used it with my original as a colour layer, I'll add the images to my thread on NGC 55. I've made a 3 frame video as well to show the difference. I'll drop that on vimeo or youtube. It makes a compelling case for more time spent on the colour for this one for me.
Of course if you do mind, just let me know and I'll remove the images.
Cheers
Stuart
No problem Stuart, I am looking forward to seeing the result.
Quote:
Originally Posted by madbadgalaxyman
Paul,
Nice to see a good and deep NGC 55, for a change.
For some reason, people seem to make shallow exposures of this galaxy, perhaps for the reason that these are "good enough" to show the boxy/irregular LMC-like central part of the galaxy (which is of notably high surface brightness.)
The outer zone of very blue structure is interesting.....do I see some poorly-defined spiral arms there? Arguably, if this galaxy were deprojected to a face-on orientation, there is just a hint of spiral arms opening in an anticlockwise direction.
Because NGC55 is so near to edge-on in orientation, it is exceedingly difficult to figure out what it would look like if it were in a face-on orientation.
In general, it could be classified as a Magellanic spiral of type Sm, due perhaps to the merest hint of spiral structure and regularity in its structure (as distinct from a bona fide irregular galaxy). But there is not a lot to go on because of the orientation.
cheers, Robert
One does get the sense of significant regular structure in this galaxy, though rather chaotic and entropic; for instance, there is a rough and ready bulge-like structure of older stars surrounded by an annulus of much younger stars.
Thanks Robert for your considered comments. I found one or two images out there in cyber land that sort of hinted at the spiral structure. Some of the commentary suggested it might be a barred spiral, but like you said it is so hard to tell at this angle. Great object to image and one that I will redo again with the RC12 in the future.
Quote:
Originally Posted by Rigel003
Looks great Paul. Nice star colours and hints of pink in the HII regions. the brighter portion has been dodged well and there's so much detail. The background sky looks a little lumpy - not sure if this is faint stars or a bit of noise still, despite the marathon exposure.
Yeah the sky does look a little lumpy, but I think this is the smoothing I used. I really needed a lot more data in the lum to allow the stretching I wanted to do. There is also a bit of gradient going on, but I think that is caused by a night of high cloud in the mix.
Quote:
Originally Posted by naskies
Great work, Paul. I think that's some of the best colour I've seen in NGC 55.
Dave the colour was my main focus for this object. Don Goldman's image of this object and Martin Pugh's are key stone reference for me. Both have great colour and fine detail.
Quote:
Originally Posted by PRejto
Great photo, Paul. I agree about the colour. It's super!!
Peter
PS Obviously your guiding is working perfectly!
Guiding really makes an image. Tight stars lead to good detail showing in an image. Just even slightly eggy stars results in a loss of detail. Good seeing is also needed but if you have tight stars your half way there.
That's quite good Stuart.
It would also be interesting to see both you & Paul could share the RAW frames & stack them together & then reprocess.
How would you handle the scaling to do that?
Is it possible?
I am looking at another wide field set up down the track, but I don't think I will go with a fast Newt. However, never say never.
