Caldwell 49

[Paul Haese]

I was going to delay posting this image because of the plethora of Rosette images about at present. It seems we have all got the bug, myself included. I managed to get a couple of nights imaging in despite Win 7 not recognising the camera on one night, which resulted in losing about 5 subs.

As to the nebula itself, this is located in the constellation of Monoceros at a distance of between 4900-5200 light years. It seems no definite distance as been ascertained as yet. The nebula is about 130 light years across and contains quite a few high radiation emitting stars which drives the emission nebulosity. In traditional RGB light the nebula presents as a rosette or rose. With the Addition of narrow band data the nebula does as coined by Mike present a tunnel or sorts and a lovely display of bubbles of gas.

The object had long been on my imaging list but I was not able to capture it all prior to obtaining a reducer for my TSA. And; it is quite north in declination and just clears my roll off roof on the observatory. The processing is I think to my liking on this occassion after several reprocesses, but it still contains some darker rings (blue stars outer halos present quite dark when super imposed on deep red) in the darker parts of the nebula. I did try Peter W to keep this to a minimum (you are always picking me up on that :)), but I think I will need to learn some more processing ideas on reducing this problem. Isolating the stars through layers is going to be a must for this type of emission nebula.

Of note is that on my Ha data I had really large halos (aka reflections) on the brighter stars. This was over 2 nights and it appears just like in Chris Venters image. Although I note he says his are in his RGB set and not Ha. Not seen these halos before and might need to investigate the cause. Ideas would be appreciated.

Click here (http://paulhaese.net/Caldwell49RosetteNeb.html)for the image.

[strongmanmike]

Caldwell 49 huh...? Code for The Rosette he he.

Not bad Paul, I like the wafty look you have finished with, reminds me of rasberry gelato :). This object has so many faces depending on what filtered light you gather and how you process it, which is great really. Some nice colouring especially in the stars going on there too. It would be worth working some more on the dark rings around the stars as this would improve the over all impression.

Nice job

Mike

[Paul Haese]

You like that? I thought it would attract a few more views, rather than calling it by its common name.

You're right about the different views. I did at least 6 or 7 reprocesses and each time I found another part of the data that I brought out. In the end I did a combine and layer of all the stuff I like.

With regard to the rings are you using selection of the stars and then doing a layer mask and lightening the halo? I have seen some thing like that on Adam Blocks tutorials which controls star size. Perhaps that might work for this problem too?

[Rigel003]

Lovely photo. The colours just kind of slap you in the face (in a good way).

...I know you just didn't want a thread heading that said "Rosette" but I really wish people wouldn't use the Caldwell catalogue. There's plenty of good NGC numbers out there (although I think the Rosette has about three of them).

[Bassnut]

Excellent Paul, and crafty view grabbing ploy :-)

[Paul Haese]

Thanks Graeme.

Yes plenty of NGC numbers, but not part of the plan. ;)

Thanks Fred, I am leaving this one for now, unless someone can tell me how to remove those few dark halos.

[gregbradley]

That's a very striking image Paul.

The star halos aren't that noticeable to me.

It may be you didn't feather at some point the star selection so it has a harsh edge.

It could be your blue stars have larger FWHM than the red and green.
You could go back to your master red, green and blue and measure the FWHM of the same stars in CCDstack (double click on a star) and see if the FWHM values are much worse in blue (they often are).

Then try deconvolution/positive contraint -say 40 iterations, increase the radius a tad and pick that same star as a reference. Run decon and remeasure. When you get blue FWHM on that star the same as red and green then try a new colour combine and see if that handles it.

Jase had a fairly complex way of handling halos. Its in the processing tips area. I have a copy of it if you need it.

Photoshop actions reduce small violet halos can work but it really just desaturates the blue halo. Its not bad.

Reflection halos around bright stars I would guess are reflections off your reducer and CCD window. Roland Christen has commented on the single layer anitreflection coating of the QSI CCD window causing reflections on the AP group. Perhaps it only happens with faster F ratios with different light angles.

Only thing I can think of to try to stop that is a black cardboard mask with a cutout for only the CCD chip put over the CCD window to reduce stray light getting in and causing unwanted reflections. Short of that check for any shiny bits in adapters for the reducer or the reducer itself.

Greg.

[Paul Haese]

Thanks for the tips Greg. I will go and check things out for Jase's tut.

You could be right about the QSI window. The system is pretty fast right now, and previous images such as the Lagoon I did some time ago was without the reducer. I am not too miffed about it, but I will look into it a bit more. I might go and take a look around the AP yahoo group. Food for thought for sure.

[atalas]

Great effort Paul.

[SkyViking]

Very nice Paul, and all the anima... ehm I mean Bok globules are really crisp. :P
Great work! thanks for the view.

[iceman]

Lovely image Paul, love the constrast in the bok globs.

[Paul Haese]

thanks guys, much appreciated.

[Stevec35]

Nice Rosette Paul. The star artifacts are noticeable but don't detract too much on what is a good image.

Cheers

Steve

[Paul Haese]

I think the star halos are more noticable in the darker (aka deep red) section of the nebula on the right hand side. Would you agree or do you think it is generally over the entire image?

[multiweb]

Great shot with vibrant colors and a lot of depth. Love the saturation. :thumbsup:

[spearo]

looks great
frank

[Stevec35]

Yes - that's definitely the way I see it. There is also a smaller area on the left. The stars look great everywhere else.

Cheers

Steve

[Craig_L]

Great image and detail Paul. I hope you get to the bottom of the star halos.
Can't remember I have noticed them on your previous images, but to me they seem consistent over the entire image. What make filters are they?

[Paul Haese]

Astronomiks Craig. Half the problem is that the stars are over saturated to some extent because of my sub duration. I expect to see some halos because I like to image deep. Where it bothers me most is amongst the deep red section. I will take a look at this sometime soon and work out how to control the problem, then do a reprocess.

[Ross G]

A beautiful photo Paul.

I love the colours.

Ross.

[mill]

Very nice pic Paul and yes the star holes are noticeable but i think with a reprocess it will become a beauty of a picture.

[RickC]

Another fantastic image Paul
the TSA+reducer gives a lot of detail