APOD: Hanny s Voorwerp (2011 Feb 10)

[zloq]

Can you provide a reference to such a tube - either for purchase or that someone built in a lab? If you have expertise in the topic area - I assume you have references. If it is trivial to make such a tube - and you have done it yourself - surely there is a paper or product somewhere.

Can you describe the physical process by which you excited the doubly ionized oxygen - and how you avoided collisional deexcitation in a small tube - when the lifetime of the forbidden transition is on the order of minutes?

Can you provide a pointer to an observatory that has an [OIII] discharge tube providing a reference spectrum line?

The [OIII] emission line was a puzzle since Huggins first observed it ("nebulium") spectroscopically in 1864 until it was theoretically matched to [OIII] in the late twenties. People had already been blasting gases in discharge tubes for some time and never seen that emission line - which is why it was a puzzle. I don't know any reference to creating it in the lab - though I did find mention of [OI] and a few other much shorter-lifetime and lower energy forbidden lines created in the lab. It is possible that with an exotic, non-equilibrium setup the emission could be generated - but I know of no one who has done it, or why they would want to.

There are lots of discharge tubes for purchase, and they are used for calibration in spectroscopic work - but I don't know any that output a forbidden line prominently. Some of the shorter lifetime and lower energy ones may appear in the spectrum - but the long ones like [OIII] are rather unlikely.

You can, of course, have oxygen glowing in a discharge tube - but it is emitting allowed transition lines that have very short lifetimes.

I think dslrs are great at perceptual color - that's why they sell so well and people use them so much. They may not be great for quantitative photometric work, though, but they are tuned to human perception of color - which is the topic here.

zloq

[Chris Peterson]

Can you provide a reference to such a tube - either for purchase or that someone built in a lab?

I already did.

Can you describe the physical process by which you excited the doubly ionized oxygen - and how you avoided collisional deexcitation in a small tube - when the lifetime of the forbidden transition is on the order of minutes?

I don't (and didn't) make the tubes. They were commercially available devices that were incorporated into other instruments. The production of such devices is not an area of personal expertise.

I think dslrs are great at perceptual color - that's why they sell so well and people use them so much. They may not be great for quantitative photometric work, though, but they are tuned to human perception of color - which is the topic here.

Well, "perception" is the key point, I guess. Different people see color differently. I can put a 5 nm wide OIII filter in front of my camera and take a picture, and the resulting solid blue-green color I see on my screen looks very different from what I see looking through that same filter. And given the nature of the blue and green filters used by the camera, and the assumptions made by the de-Bayer algorithm, that is unsurprising.

FWIW, doing this experiment with a Canon 300D and a Canon 40D, using exactly the same settings, produces two completely different colors.

[neufer]

Can you provide a reference to such a tube - either for purchase or that someone built in a lab?

I already did.

Not really.

Can you describe the physical process by which you excited the doubly ionized oxygen - and how you avoided collisional deexcitation in a small tube - when the lifetime of the forbidden transition is on the order of minutes?

I don't (and didn't) make the tubes. They were commercially available devices that were incorporated into other instruments.
The production of such devices is not an area of personal expertise.

Possibly a continuum light source with a filter in front of it?
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I actually have an idea of what might have happened here:

Clearly aliens in the form of domestic animals took over Guffey, Colorado, a long time ago:

<<Guffey, Colorado, population 26, is semi-famous for electing animals Mayor of Guffey, although such an office does not officially exist. The last known Mayor of Guffey is a cat named Monster (elected in 1998). The town is perhaps less famous for the annual Fourth of July Chicken Fly, during which chickens are ejected from a mailbox atop a ten-foot-high platform; prizes are awarded for distance.>>

When these aliens finally got around to probing Peterson he distracted them and quickly reached for their nebulium lamp like he was supposed to.

Unfortunately the aliens were very methodical and kept everything in alphabetical order so Chris accidently pushed the Neuralyzer button as well thereby wiping out his memory. So now Chris thinks that he purchased his nebulium lamp from from Melles Griot.

[Buster]

Hanny's Voorwerp looks like a chicken to me. Perhaps it's really Henny's Green Chicken, and she's looking at her pink nest (2497).

Maybe you can answer a question for me. Why didn't Armstrong land on the moon when it was full, so he would have had a larger target?

[NoelC]

Why didn't Armstrong land on the moon when it was full, so he would have had a larger target?

Well the answer is obvious to even the most casual observer: ANYONE could have done THAT.

-Noel

[neufer]

Click to play embedded YouTube video.

Why didn't Armstrong land on the moon when it was full,
so he would have had a larger target?

Well the answer is obvious to even the most casual observer:
ANYONE could have done THAT.

• Full moon and empty Armstrong
  Tonight I'll use the magic moon to wish upon
  And next full moon, if my one wish comes true
  My empty Armstrong will be filled with you

[Beyond]

SHEEEEEEEEEEEEEESH