Some NIR work *now with colour*

[multiweb (Marc)]

We had a good run of clear in Sydney all this week so I made the most of it. I did a couple of comparative panels on the trap in Orion and the keyhole area in Carina.

Orion is getting low very fast so the quality and guiding isn't consistent but I was able to guide much better on Eta. Start of the week had pretty bad seeing but last night was much better. Although the moon is up and brigth now. Can't have it all would be too easy...

Keyhole - 9hrs in 5min subs. 1.8m FL. QHY9/IR >700nm
Stand alone here 1:1 [1.62MB]
Side by side with LUM here [1.31MB]

Trap in Orion: 3hrs in 5min subs. 1.8m FL.QHY9/IR >700nm
Side by side with LUM here [573KB]
Not particularly happy with that one but given the conditions that's all I could get.

Enjoy the views and thanks for looking.

PS: added some color for the keyhole. IR goes red, visible goes blue.
Big one 1:1 here 1:1 [4.98MB]
HD (1920) here [2.26MB]
User friendly here [1.14MB]

also some color for the trap. Not as good. Low on the horizon and hard to guide.
Big one 1:1 here 1:1 [6.18MB]
HD (1920) here [2.63MB]
User friendly here [1.16MB]


Sorry about the size. Colour adds to it.

[Dennis]

Thanks for posting your results Marc, NIR looks to be a very interesting approach from the comparisons you posted, time for me to start swotting up on the topic.

Hmm, some hours went into capturing these eh!

Cheers

Dennis

[RobF (Rob)]

Yes, great stuff Marc.

I'd be interested to hear your thoughts on the pros and cons of IR versus Ha versus NII narrowband? It sounds like you may need more IR data than even SII normally requires? I don't think you've shot NII before, but looking at Bert's work recently wonder about merits of NII versus IR. IR certainly seems to be pulling in the interesting faint clouds while subduing the milky way stars.

I've learned so much about the orientation and relative brightness of objects from your widefields over the years, apart from just enjoying them too

[multiweb (Marc)]

Originally Posted by Dennis

Thanks for posting your results Marc, NIR looks to be a very interesting approach from the comparisons you posted, time for me to start swotting up on the topic.

Hmm, some hours went into capturing these eh!

Cheers

Dennis

Thanks Dennis. Rolf does much better composites with LRGB data on his website. I don't get to leave the rig on the pier from one night to the other very often but on occasions we have a good run with no rain so no need to pack up. Making the most of it until this week-end hopefully.

Originally Posted by RobF

Yes, great stuff Marc.

I'd be interested to hear your thoughts on the pros and cons of IR versus Ha versus NII narrowband? It sounds like you may need more IR data than even SII normally requires? I don't think you've shot NII before, but looking at Bert's work recently wonder about merits of NII versus IR. IR certainly seems to be pulling in the interesting faint clouds while subduing the milky way stars.

I've learned so much about the orientation and relative brightness of objects from your widefields over the years, apart from just enjoying them too

Thanks Rob. I don't think you can compare the two really. NIR is on 700nm and well over. Ha/Oii/Sii/Nii is all emission stuff up to 700nm, gas clouds. To get the benefit of Nii you need a very tight filter. My 7nm Ha covers Nii as well so I wouldn't be able to separate the two like Bert does. Narrow filters (3nm) cost a fortune.

IR will show you stars hidden deep in gas clouds. With the filter I use I cover anything from 700nm to 1000nm which is the limit of the CCD. If I wanted to do an IR 'RGB' palette I'd use this as the IR 'LUM' and get narrower filters at 750/850/950 for R, G & B. You can actually buy these in a set. Familiar objects would then look very different so you could image the same stuff in a different light.

The comparison shots I did are just visible (straight clear LUM) vs. IR. I removed the IR cut filter from the camera which explains the blooming. Although they all look monochrome there's no Ha in that. I might actually shoot some tonight as the moon is very bright now.

IR does get affected by skyglow/moon glow. I guess finding a guide star in an OAG with the full moon is the main issue. Funny enough the subs I imaged through the clouds in IR weren't as bad as when I did Ha. Seems to cut through better. Weird.

[jase (Jason)]

Excellent Marc! You can really see the differences between the emission lines. M42 really shows that Ha brings the finer detail in structures, where as NIR can't be mistaken for a much larger bandpass window where it is capturing the faint larger structures. I like the comparison you've displayed. I could see this being used as a luminance perhaps layered with Ha data. You've needed to put in considerable exposure time to get these solid results. It looks worth the effort. Is your set up all reflecting? i.e. there is no glass in the imaging train. Any refractive elements may introduce an IR cut off so results are less than optimal. This also applies to ccd cover slips where in most cases it is removed to improve QE.

[multiweb (Marc)]

Originally Posted by jase

Excellent Marc! You can really see the differences between the emission lines. M42 really shows that Ha brings the finer detail in structures, where as NIR can't be mistaken for a much larger bandpass window where it is capturing the faint larger structures. I like the comparison you've displayed. I could see this being used as a luminance perhaps layered with Ha data. You've needed to put in considerable exposure time to get these solid results. It looks worth the effort. Is your set up all reflecting? i.e. there is no glass in the imaging train. Any refractive elements may introduce an IR cut off so results are less than optimal. This also applies to ccd cover slips where in most cases it is removed to improve QE.

Thanks Jase. I added some colors after reading how Rolf did his blends. Makes the picture and data repartition much clearer in one pic.

I used a 90mm APO (refractor) with a FFC set at x3. So that gives me 1.8m (3x600mm). I use a lodestar and an OAG. It's a little tricky and on the limit of the G11 but with no wind and a lot of swearing and arm waving it's ok.

I removed the IR cut nosepiece on the QHY9 and used a clear nosepiece I had from the QHY8 after chatting with Theo. QE is not too shabby still over 700nm but it deeps really fast after 900nm.

[naskies (Dave)]

Very interesting, Marc! Out of curiosity, is shooting in IR susceptible to light pollution / moon / etc?

[multiweb (Marc)]

Originally Posted by naskies

Very interesting, Marc! Out of curiosity, is shooting in IR susceptible to light pollution / moon / etc?

Thanks Dave. It was last night because the moon was so bright but until then it was fine with the moon glow. LP is not an issue at all. The filter is so dense even my EL sheet didn't shine through it. I couldn't do flats.

[naskies (Dave)]

Originally Posted by multiweb

The filter is so dense even my EL sheet didn't shine through it. I couldn't do flats.

Try pointing it at your BBQ

[multiweb (Marc)]

Originally Posted by naskies

Try pointing it at your BBQ

The thought crossed my mind... I was starting to think how to get the hot plate in front of the aperture but then I thought what's the odds of getting the right wavelength.... nah...

[Dennis]

Added colour looks nice Marc!

Cheers

Dennis

[DavidU (Dave)]

The keyhole in colour is beautiful.

[multiweb (Marc)]

Originally Posted by Dennis

Added colour looks nice Marc!

Cheers

Dennis

Thanks Dennis. I think it works well. Highlights the hot spots nicely.

Originally Posted by DavidU

The keyhole in colour is beautiful.

Thanks a lot David. Glad you like it.

[gregbradley]

Great work Marc. I love the golden and light blue colours this is producing. Some new ground being covered here.

Greg.

[peter_4059 (Peter)]

Interesting stuff Marc. Where is the NIR filter from?

[multiweb (Marc)]

Originally Posted by gregbradley

Great work Marc. I love the golden and light blue colours this is producing. Some new ground being covered here.

Greg.

Thanks Greg. Hardly. Rolf's been at it for a while now.

Originally Posted by peter_4059

Interesting stuff Marc. Where is the NIR filter from?

Thanks. You can get it here.

[jase (Jason)]

Very cool! The colour images have a spitzer space telescope feel to them.

[David Fitz-Henr]

Great work Marc; I particularly like the colour version of the keyhole! IR work now ... you certainly have your fingers in a lot of pies, but you still seem to produce great results!

[multiweb (Marc)]

Originally Posted by jase

Very cool! The colour images have a spitzer space telescope feel to them.

Thanks Jase. A mate of mine said that NIR is actually the cooler, not the hotter stuff. Visible is always hotter? So I might mirror the palette. I also have some nice Ha that I'm trying to incorporate as the ridges and dark boks are better defined. So I'll play with it all tomorrow and rotate the palettes for a bit for fun.

Originally Posted by David Fitz-Henr

Great work Marc; I particularly like the colour version of the keyhole! IR work now ... you certainly have your fingers in a lot of pies, but you still seem to produce great results!

Thanks David. I sure learnt a lot about guiding at long FL this week. What a pain... All the motivation I needed to dust off the AO. Widefield is evil. It's like getting fat.

[Ross G]

Amazing work Marc.

I really like the colour version.

...and here am I thinking you had run out of pies to dig your fingers in!....

Good luck, your an inspiration.


Ross.