NGC55 17.5 hours

[Paul Haese]

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.

Click here (http://paulhaese.net/NGC55TSA.html)for larger image.

[RickS]

That's nice, Paul! A lot of detail for a smallish scope.

[Paul Haese]

The mighty TSA102 does really well. It looks like a straw on the PME but I cannot complain about its performance.:)

[alpal]

Nice shot Paul.
What caused the slight diffraction spikes?

cheers
Allan

[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.:thumbsup:

[multiweb]

Some great colors and details in the galaxy. Pretty cool. :thumbsup:

[Paul Haese]

Thanks all,



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.



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.

[TimberLand]

I would have to agree with the fast newtonian but I'm biased.

Diffraction spikes, bring them on, optical artefacts that show a system is working as it should are golden.

Justin

[allan gould]

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

[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??

[Paul Haese]

Thanks guys,



Hey thanks Allan, really appreciate that. :)




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 .:thumbsup:

[rat156]

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

[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.

[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.

[naskies]

Great work, Paul. I think that's some of the best colour I've seen in NGC 55.

[PRejto]

Great photo, Paul. I agree about the colour. It's super!!

Peter

PS Obviously your guiding is working perfectly!

[Paul Haese]

No problem Stuart, I am looking forward to seeing the result.




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.



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.



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.




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.

[rat156]

Here (http://www.iceinspace.com.au/forum/showthread.php?t=113049) it the comparison.

Cheers
Stuart

[alpal]

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?

[gregbradley]

A beautifully clear, colourful and pleasing image. Well worth the effort.

Greg.

[Nicola]

Beautiful! I wish I could get such images...

[LucasB]

What a beautiful image Paul, especially for a faint galaxy like NGC55. Love the rich colour! Apparently there is a fix for the diffraction spikes for the 8300 microlens chips. I have been informed by a fellow IIS member that if you download CCDOps Version 5 from SBIG and go to Fix ME spikes in the menu it can remove them. Haven't tried it myself but if you want to have a crack let me know how it goes. Works on fits files.

Lucas

[Shiraz]

excellent image Paul. The bulge is particularly interesting and clearly defined.

[madbadgalaxyman]

Yes, NGC55 sure looks more regular in deeper exposures. Not surprising, as it is actually a regularly rotating disk structure (as shown by the rotation velocities of its neutral atomic hydrogen gas).

Low luminosity spiral galaxies are not "pretty things" because they are invariably somewhat chaotic in their structure (rarely do they have very well-defined spiral arms). However, much of this irregularity is confined to the distribution of luminous young stars.
[[ maybe M33 is only "pretty" (= strongly two-armed) because of an interaction with M31 ?!? ]]

Here is the GALEX image (downloaded from GalexView interface), which was made from two filters: the Far Ultraviolet band plus the Near Ultraviolet band.

149471

The older stars are seen in the NUV band, which is displayed as yellow. The recently formed luminous O and B stars are extremely prominent in the FUV band, which is displayed as blue.
(even a small amount of current star formation causes the galex FUV band to detect a lot of light)

Any spiral arms that are currently forming stars will "light up like a floodlight" in the galex FUV band. Older spiral arms won't.

Sometimes, I resort to a bit of defocussing of an image to try to get a handle on the main structures in less regular galaxies like this one. Better still, go to 800 nanometers and longer in the wavelength of observation, so as to get rid of the chaotic dusting of superluminous stars.

Here is a really fun comparison, the galaxy NGC 247 as seen by Galex:

149472

My morphological notes (from multi wavelength images) for NGC 247 say "probably one-armed, possibly barred", which is very typical for a lot of low-luminosity spirals.

[strongmanmike]

Nice work Paul, some nice colour variation in what is a pretty boring galaxy really, so well done :thumbsup: 17.5hrs?..really? Hmmm?...not sure I would have persevered that long.. even with 4" :question:

Mike

[astronobob]

Hi Paul, That an awesome image, plenty deep for a galaxy which gives it a real appealing Glow. fantastic !
And yeah, i can imagine you saying that the scope was looking like a straw :)
Real nice image Paul.

[Ross G]

Beautiful colour and detail.

A great galaxy photo Paul.


Ross.

[Paul Haese]

Thanks guys,

Mike I am following Martin's advice and even still don't have enough time. His advice to me last year was go 20-30 hours minimum. I have found with 20 hours of data the processing tends to be a lot easier and allows so much more stretching. You are lucky with the diameter you have and the field of view, plus the extra cooling. It would be nice to have that, but not within current budget. :)

Thanks for that extra info Robert. Appreciated.

[DJT]

That's a great image, Paul. Love the processing etc.

Thanks

[stevous67]

17.5 hours. I'm jealous. Good job Paul, very nice result.

Steve :sad:

:prey: for clear skies this new moon!

[Paul Haese]

Thanks guys. Automation is king when it comes to data gathering. Lovely nights sleep last night while the scope collected data on two objects I am working on. That's how you get 17.5 hours Steve.;)

[strongmanmike]

Yeeees....wooould be nice :question: :fishing:

Mike

[Paul Haese]

It could be yours too Mike. You just have to give up the NJP and automate your dome. Not much to do.;)

[strongmanmike]

Not much to do???? :rofl: Hmmm? firstly, ya got a higher paying job for me :question: :lol:

Would be good...would be good.....

[Paul Haese]

Yeah I hear their hiring in the labour party.:P Sell that old tired NJP and get something with a home position and you will be set.:thumbsup:

[strongmanmike]

Hey I would be interested in doing that actually, just too many more experienced people want to fight the good fight :doh: good luck to them ;)



One day..... :thumbsup:

[Bassnut]

"good fight", no, thats wrong, but the "fight", thats true, give you that.

[Bassnut]

Top work Paul, well done.

[naskies]

You should create an Australian Astrophotography Enthusiasts Party and become a senator... I hear the pay's pretty good ;)

[Rex]

Beautiful rendition Paul, the most colourful I have ever seen of this galaxy.

[strongmanmike]

You bet and side with an eccentric billionaire and fight for dark skies too :stargaze: yeeeahh baby :D...hmmm? could be something in that :question:

[strongmanmike]

:fight: for the NBN oh yeaaaaah!!...haven't lost all hope that Turnbullcrap won't finally see the light :thumbsup: