Ngc 3576 & Ngc 3603

atalas · #1 24-01-2009, 02:24 PM

Hi again all

This is another shoot from the New Year weekend but I must say not quite what I was expecting.

NGC 3576 & NGC 3603...a favorite ! I love the extended arches you see in the High Res shots of NGC 3576 but,unfortunately I could not get them to lift in this shot.

It could be that I needed higher res instrument or maybe Ha added to get these wonderful arches,or maybe just mega data!.... I'm hoping that those guy's who have experience with this object can jump in and let me know what It takes to get this Neb to Pop!!

Location: Magellan Observatory(Lake Bathurst,N.S.W)
Telescope: FSQ106ED
Camera: SXVF-M25C
Guide: ZS66SD/QHY5
Mount: AP600E
Exposures: 6 x 20 minutes
Software: AA4/CS3
http://www.atalas.net/components/com...ate=&location=

richardo (Rich) · #2 24-01-2009, 02:44 PM

Hi Louie,
this is a pretty nice image with a ton of stars.

I would spend another 1- 2 hours on just data.
You'll probably find better colour saturation.
I say this as the blue stars are very light and not all that well defined as such.
Have you done a G2V star calibration with your setup??
If not, this well certainly help when processing, taking all the guess work out of colour balance.
Also as you said, Ha would definitely bring out the HII areas and this will also make the objects appear more 3D.
Contrast masked and used sparingly to dark ridge/ HII areas can also help.

Still, go for more data and take it from there.

Nice setup Louie.
My astro buddy here where I live has a Q and let me say, this is one fine piece of kit!!

Look forward to a repro with more data

All the best
Rich

atalas · #3 24-01-2009, 05:02 PM

Thanks Rich!

gregbradley · #4 26-01-2009, 08:54 PM

Hi Louie,

Nice capture but as you say the nebula is pushed to the background by the stars.

I just imaged this one myself and it is a bit of a tricky one to get to look just right. The stars in the background can be dominating.

It is very strong in the Ha and comes out beautifully in Ha. How you blend in the Ha to maximise that is another story.

But yes, you'll need Ha and probably 2x2 binning with your MX25C.

The best I have seen of this object is by Ken Crawford and he did narrowband which I suppose pushed the stars back and brought up the
nebula which has some nice delicate arches and tendrils.

Greg.

atalas · #5 27-01-2009, 06:35 AM

Hi Greg

Thanks for you time mate ! 2 x 2 bin for Ha ? the loss of res won't matter Greg? I'll give It a go next I get a chance mate.

Greg,do you think that 20 minute subs on this color shot just makes It more difficult to deal with a dense star field ? maybe I should re shoot 10 minute subs and then a few hours of Ha?

gregbradley · #6 27-01-2009, 10:51 AM

Quote:

Originally Posted by atalas

Hi Greg

Thanks for you time mate ! 2 x 2 bin for Ha ? the loss of res won't matter Greg? I'll give It a go next I get a chance mate.

Greg,do you think that 20 minute subs on this color shot just makes It more difficult to deal with a dense star field ? maybe I should re shoot 10 minute subs and then a few hours of Ha?

With one shot colour 2x2 binning makes sense as the Bayer matrix means only every 4th pixel has a red filter anyway. The blue and the green will be contributing almost nothing so I think there would be very little loss of resolution. I know one guy (Chan) who uses 1x1 and perhaps he gains a tad but the extra exposure time and possible extra noise from the 3 pixels that are hardly generating any signal may be a loss. You could check for yourself but I used to use 2x2 on one shot and it worked very well. It didn't seem that much different to 1x1 with a mono.

Not sure about the stars being so dominating. I think Ha and if you have it - O111 would be the go. Ken Crawfords excellent shot is in narrowband and the stars are really small and hardly impinge at all. The gas loops stand out. I wonder if that shows up a lot in O111 like the Vela supernova remnant.

I sometimes use 10 mins to get sharper stars as sometimes (oftentimes) my dark site is windy and 15 - 20 mins exposes me to more chance of wind damaged subs. But yeah 10mins may be the go. I used 10 mins for mine but mostly because of the wind.

Greg.

atalas · #7 27-01-2009, 02:34 PM

No OIII Greg,but I can get one and maybe I'll get the bug for narrowband imaging.

Thanks so much for your time !

gregbradley · #8 27-01-2009, 08:04 PM

Hi Louie,

I had a look at your image in Photoshop.

I managed to get the stars down, some colour into them and the nebula brought up. Quite a nice image I think.

You want me to publish the result and what I did?

Greg.

atalas · #9 27-01-2009, 08:13 PM

Hi Greg

Sure you can mate...you have my attention!

gregbradley · #10 27-01-2009, 09:23 PM

Here it is:

http://www.pbase.com/gregbradley/image/108596154/large

The stars may be a bit too coloured now but anyway:

1. 2 or 3 runs of Noel Carboni's "reduce star size" (this is basically resize up x 4 times, then minimum filter then resize down).

2. 2 runs Noel Carboni "increase star colour". This is basically using the colour range tool to select out stars after resizing up x 4 and using saturation and resize down possibly a bit of gaussian blur in there as well.

3. Curves on red channel to bring up the red nebula more.

4. Sponge tool set to saturate 5% and rubbed on the red nebula areas.

5. Not much else.

Greg.

atalas · #11 28-01-2009, 05:56 AM

I think you've taken It a bit too far Greg...lost the natural look,don't you think?

gregbradley · #12 28-01-2009, 12:48 PM

Quote:

Originally Posted by atalas

I think you've taken It a bit too far Greg...lost the natural look,don't you think?

Yes it is a bit overwhacked but the neb can be made to come out with more subtle processing without losing the naturalness.

Greg.