The Emerald Firebird is famous its ineluctably green feathers, and for dancing tip-toe in south-west Carina.
The thumbnail sketch shows some additional features in the region of the firebird's breast. Vulcan's Anvil, the horizontal yellow feature, has been struck so hard that it has generated quarks, anti-quarks, a bat (sketched in blue), and various pieces of molten gold.
One of the earlier blows has released a small slice of lemon, seen isolated in the sky below the drips of gold.
To the left of the bird's long neck is a tiny, intriguing patch of violet lightning, of unknown nature, but perhaps similar to the one we previously found in the Gabriela Mistral nebula.
Please do not challenge the Firebird for having emerald plumage. It is in its Buddha-nature to be so, and it pecks very hard. In more detail, this is presumably another example of an early star-forming region, where there is enough gentle UV to cause H-alpha emission, but not much in the way of super-large, ultra-hot stars that would produce OIII emission. However, we do note NII emission (red) along the bird's head, neck, and breast, and in the tail feathers. SII (not shown) proved to be utterly negligible, making it more plausible that this is a very young star-forming region.
This quickie of NGC 3572 (Big one here) is to celebrate last night's clear sky.
Green: H-alpha; Blue: OIII; Red: NII. 2 hrs each in 1hr subs. Aspen CG16M on 20" PlaneWave CDK.
Very nice. You are having some good results with those 1 hour subs.
How do find them in terms of sharpness and star size?
Greg.
Hi, Greg,
Last night seeing was good but not brilliant. The FWHM of a 10 second H-alpha focus frame was 4.0 pixels, or 2.4 sec arc. The FWHM of a non-burned-out star in a 1 hour sub was 4.7 pixels, or 2.6 sec arc. Thus all the accumulated bumps and glitches of hitting bits of grit or tight spots or rough teeth, field rotation, differential flexure (the focuser is still a teensy bit floppy), bats flying through the field, etc, only made things about 17% worse.
It's a long time since I did the maths and I've lost all the source documents, but from memory, going any longer than 1 hour is not justified because the contribution of read noise to the total image noise is already very small.
The biggest disadvantage is that if you've only got two one-hour H-alpha subs (as opposed to say a stack of 12 ten minute subs) you can't do any automatic cosmic ray and satellite trail rejection. We just leave the cosmic rays in - they are, after all, perhaps the most spectacular deep sky objects in the image!
The second biggest disadvantage is intermittent cloud. We set up at dusk, and leave the system to run a fairly complicated script, going to a suitable focus star and refocussing after each frame, changing filters, returning to the object, reacquiring guide stars on the two guide cameras. If a small cloud comes, we lose one hour. But that happens quite rarely. And we can program the beast to do two objects in the one night. Last night it did the Emerald Firebird in NB until 1am when the moon went down, then went on to NGC 5128 in RGB, and finally rattled off some darks.
We set up at dusk, and leave the system to run a fairly complicated script, going to a suitable focus star and refocussing after each frame, changing filters, returning to the object, reacquiring guide stars on the two guide cameras. If a small cloud comes, we lose one hour. But that happens quite rarely. And we can program the beast to do two objects in the one night. Last night it did the Emerald Firebird in NB until 1am when the moon went down, then went on to NGC 5128 in RGB, and finally rattled off some darks.
Best,
Mike
Hmmm I gotta get me a setup like that, grumble grumble, humf.......
Very interesting shot guys and sadly...again, I do see what you see too (only a Flamingo, all be it greeny)
Wow! Haven't seen her before, well found - kind of reminds me of a cosmic mermaid
At risk of overstepping my boundaries, had you considered something along the lines of this colour scheme?
Lovely image Mike and Trish, I always look forward to seeing your new photos. ... But it is very interesting to see results with few loooong subs, as opposed to stacking numerous short ones.
Quote:
Originally Posted by cometcatcher
1 hour subs!!! With a 20" ...
Thanks, Slawomir and Kevin. Really long subs are good if you're going after very faint stuff in narrowband, and are easy if you have a permanent mount with good polar alignment, a dome to keep the wind off, deep wells and a dark sky so you don't saturate, and off-axis guiding to avoid differential flexure.
Quote:
Originally Posted by SimmoW
Nice one M&T, wow 1 hr subs, getting some subtle detail there. Maybe a bit yellow for my liking, but thats just my HO!
Simon
Thanks, Simon. Andy has perhaps provided a solution.
Quote:
Originally Posted by Andy01
Wow! Haven't seen her before, well found - kind of reminds me of a cosmic mermaid
At risk of overstepping my boundaries, had you considered something along the lines of this colour scheme?
Lovely fov as well
Andy
Thanks, Andy. We actually like your rendition. We've doubled the data now, so we might have a play.
Hmmm 
I gotta get me a setup like that, grumble grumble, humf.......
Very interesting shot guys and sadly...again, I do see what you see too 
(only a Flamingo, all be it greeny)
