UV imaging

[multiweb]

I have a Baader U Venus filter (https://www.baader-planetarium.com/en/filters/baader-u-filter-(venus-and-uv---350nm).html) which covers 320nm to 380nm and did 12h of UV channel in 10min subs on eta Saturday and Sunday night. Same framing as my IR channel so I could do a bicolor with UV mapped to blue and IR mapped to red. UV imaging is hard yakka so I'll never complain about Sii anymore. The moon was up and the contrast was a little better when it went lower but it still doesn't seem to be affected by skyglow too much, same as IR which is great for me in my "Las Vegas" backyard.

Here's the blend result UV UVIR (50%) UV and the separate channels IR, UV, then blend. There's a bit of info about the filter (https://www.baader-planetarium.com/en/filters/baader-u-filter-(venus-and-uv---350nm).html)and UV imaging here (https://randombio.com/uv.html).

Got some highres version too:

IR 121 [3336x2496 - 4.2MB] (http://www.astropic.net/astro/NGC3372_IR_FSQ106N_121.jpg)
IR HD [1920x1437 - 1.9MB] (http://www.astropic.net/astro/NGC3372_IR_FSQ106N_HD.jpg)

UV 121 [3336x2496 - 4.2MB] (http://www.astropic.net/astro/NGC3372_UV_FSQ106N_121.jpg)
UV HD [1920x1437 - 1.9MB] (http://www.astropic.net/astro/NGC3372_UV_FSQ106N_HD.jpg)

UV IR 121 [3219x2334 - 7.2MB] (http://www.astropic.net/astro/NGC3372_IR_UVIR_UV_FSQ106N_121.jpg)
UV IR HD [1920x1392 - 3.5MB] (http://www.astropic.net/astro/NGC3372_IR_UVIR_UV_FSQ106N_HD.jpg)

Enjoy the views. :thumbsup:

[Pyali]

Very interesting! Hadn’t heard of UV/IR imaging until this post

[Merlin66]

Marc,
Which camera?
The silicon based sensors usually die around 3600-3700A....

[multiweb]

Thanks Pali. :thumbsup:



QHY9 mono. Supposedly I still get ~20% QE at 350nm.

[Merlin66]

Marc,
I’m impressed if you can achieve that.....
With spectroscopy (ATIK314L) I was struggling to get a good signal below 3700A.

[gregbradley]

Nice work Marc. Always good to see a new view.

Greg.

[multiweb]

I did 10min subs @-20c, 12.6h in total. I dithered each frame. Drizzle combined in pixinsight then binned back 2x2 to native res. It is still a little noisy even after that much integration. Scope is the FSQ106N. I don't know if it having a fluorite element helps with sensitivity. I want to try with the CN-212 next as there is no glass in the imaging train.

[multiweb]

Thanks Greg. :thumbsup: Yeah I have all those filters so it's fun to try different parts of the spectrum. I also have a H beta that's close to Oiii. Might see if I can use this as a green channel maybe.

[Atmos]

Fascinating Marc!
My most recent image of Eta Carina was taken without a UV/IR filter, only whatever the bayer matrix blocks so I do wonder how much signal from these frequencies bleeds into the data. Given the amount of exposure time that you've had to put in so far I don't think it would be much compared to the straight RGB component.

[multiweb]

There seems to be a fair bit of bloating on some of the stars. I did an hour or so on M42 in UV and there are some halos and internal reflections on the brightest blue star in the field to the right of the main nebula. I've also noticed some stars almost invisible in IR flaring like a light house in UV and vice versa. I guess we don't notice that doing RGB because the Lum filters are already UV/IR cut. As you pointed out all you see in those pics is outside of the usual RGB space we image in, including narrow band emission lines.

[h0ughy]

Awesome result

[Ant0nio]

An enlightening post Marc & the blend in image 3 is quite special.
Well done for pushing the envelope :thumbsup:.
Cheers,
Tony

[DavidU]

Excellent Marc, what a cool idea.
:thumbsup:

[ChrisV]

Totally cool idea Marc. Really like it !

[multiweb]

Thanks for the feedback guys. :thumbsup:
I have bucket loads of IR shot with the old Q from the last astrofest so now with the winter milkyway slowly coming back I'll be spending a lot more time doing UV from home this winter to complement the data I already have and experiment with some psychedelic blends. :evil:

[multiweb]

Thanks Chris, glad you liked it. :thumbsup:

[Placidus]

Definitely one for the Cool Wall there Marc.


One wonders what is the source of the UV nebulosity. You kindly sent me the transmission data for the UV filter, and it's clear that negligible OIII or H-beta are going to be getting through. There are other hydrogen lines, and perhaps calcium.

[Merlin66]

Hot O B stars emit most of their energy in the UV - Black Body curve for hot stars > 20000K

[multiweb]

Thanks Mike. :thumbsup: I added it to the pics thumbnails.




Yes that's was I was reading too. I highlighted on the spectrum the area each filter covers and the corresponding QE for the QHY9.

[topheart]

Fascinating stuff there Marc!!

Cheers,
Tim

[RB]

That's sooo cool Marc!!!
I wacked on some Banana Boat SPF50+ just to be on the safe side.

And now you've got me singing "Day-O".... :cool3:

:lol:

[multiweb]

Thanks Tim. :thumbsup:



:lol: Thanks mate. The SPF50+ filter. Now I reckon you're onto something.

[codemonkey]

Very cool Marc! I don't recall seeing any amateur UV images before. Thanks for sharing!

[marc4darkskies]

Very interesting Marc!! :thumbsup: Given the earth atmosphere's relative opacity to UV and the poor QE of the camera at wavelengths less than 400nm, I'm surprised the result is so good. In any case, I'd guess what you're seeing is predominantly UV scattering from dust in the neb. A casual inspection suggests that the brightest UV responses come from the vicinity of the most luminous stars embedded near the dustiest parts of the neb. :question:

[Placidus]

That makes complete sense.

[multiweb]

Thanks Lee. :thumbsup:


Thanks Marc. :thumbsup: Yeah I didn't know what to expect at first but then when the first sub came in there was some signal in there and based on how much I had in 10min I kept going knowing I could make something out of it. I read that reflection nebs show up in UV. Emission lines Ha and others don't(?). There is a small Ha pic in the UV range in the filter spectrum for Ha. Not sure if Ha contamination is possible. I don't know enough about it. Maybe somebody can chime in.

There's a single 10min uncalibrated raw sub here (http://www.astropic.net/astro/UV/NGC3372_b1_UV_g1o113_096_235437.zip ) if you want to have a look at it.

[multiweb]

Here's what ~1.5h on M42 looks like in 5min subs.

[cometcatcher]

That's very cool, but slow! I wouldn't have the patience, or sky for it.

[Atmos]

CII has two UV emission lines between 320&380nm so it could be those that you’re seeing. You’d expect to find CII in and around star forming regions; NGC 3372 and M42.

[multiweb]

:lol: not going anywhere lately. UV imaging will keep me sane. :nerd:



Good stuff. Gotta do some more read up. :thumbsup:
Did some IR last night and the night before with the CN-212. Plenty of that and fairly easy to get at that FL too surprisingly.

[Merlin66]

C II doesn't come up on my data base as significant...
Have a look at the typical nebulae spectrum.

[Atmos]

My mistake, I was looking at 133nm haha

Attached is a table of all of the emission lines from 320nm to 380nm. They’re in angstroms which is nm*10 so the 3444 angstrom OIII line is 344.4nm.

As Ken shows, many of the emission lines aren’t strong but it gives you an indication of how many potentials there are.

[Merlin66]

http://arxiv.org/ftp/arxiv/papers/1208/1208.0380.pdf
This is the listing we generally use....