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James Webb first images – complete set of high resolution shots now live

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Re: James Webb first images – complete set of high resolution shots now live

#291

Post by randyrand »

j0e1 wrote: post #234
chaps wrote: post #64

Direct links -- Stephan's Quintet (NIRCam and MIRI Composite Image): https://stsci-opo.org/STScI-01G7DB1FHPMJCCY59CQGZC1YJQ.png Southern Ring Nebula (NIRCam and MIRI Images Side by Side): https://stsci-opo.org/STScI-01G79R28V7S4AXDN8NG5QCPGE3.png “Cosmic Cliffs” in the Carina Nebula (NIRCam Image): https://stsci-opo.org/STScI-01G7ETPF7DVBJAC42JR5N6EQRH.png Webb's First Deep Field (NIRCam Image): https://stsci-opo.org…

> “Cosmic Cliffs” in the Carina Nebula (NIRCam Image): > https://stsci-opo.org/STScI-01G7ETPF7DVBJAC42JR5N6EQRH.png Is this for real?! It looks like it came right out of a Sci-Fi movie/book. Could anyone explain how much of this is post-editing magic?

Does anyone have a simulated image of what it would look like in visible light without red shifting?

i.e. If we were moving at the same velocity of the Nebula looking with our own eyes.

i.e. What it would look like "in real life if I actually went there"

Re: James Webb first images – complete set of high resolution shots now live

#292

Post by sbierwagen »

jvanderbot wrote: post #286
sbierwagen wrote: post #257

Earlier quoted context omitted.

Image stacking to remove noise and optical artifacts, careful use of color filters to enhance contrast and pull out detail. The press release says it used Red: F444W, Orange: F335M, Yellow: F470N, Green: F200W, Cyan: F187N, Blue: F090W. The N filters are narrowband. F470N is only 54 nanometers wide: https://jwst-docs.stsci.edu/jwst-near-infrared-camera/nircam... Almost all the light in this image is way off the red e…

How does this "blueshift" compare to what we'd get if we just corrected for the relative-speed-induced redshift?

NGC3372 is inside our galaxy, just 8500 light years away. It's not redshifted by metric expansion to any appreciable degree, (A calculator I just checked gave me a z of 0.000000617) and radial velocity is a sedate ~34 km/s. (z = 0.000000115)

The redshift on the other JWST images is because most of them are of objects that are much, much, much farther away. Infrared telescopes are great for observing those, but that's not the only thing they're used for.

Re: James Webb first images – complete set of high resolution shots now live

#293

Post by WebbWeaver »

I really appreciate the work of the US Air Force Cambridge Research Laboratories for creating HITRAN. HITRAN is a molecular spectroscopic database used to look molecules in gas and atmosphere. They are the standard archive for transmission and radiance calculations. Without their groundwork we would not be as good at understanding planetary atmospheres.

https://hitran.org/ free after registration

https://hitran.org/media/refs/HITRAN-2020.pdf

HAPI (programming interface manual) https://hitran.org/static/hapi/hapi_manual.pdf

Youtube tutorials https://www.youtube.com/watch?v=NiKuigtFahk&list=PLqOG3cBizT...

It is very easy to use and might help to understand WASP-96 b transmission spectrum. https://stsci-opo.org/STScI-01G7NBXDHYYSVBP2M476PRGG3A.png

https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_...

Re: James Webb first images – complete set of high resolution shots now live

#294

Post by mensetmanusman »

whiteboardr wrote: post #137
jacquesm wrote: post #99

Earlier quoted context omitted.

The difference between 'actual science' and 'some touched up version of objects in our universe' is smaller than you might think: no matter how good your eyes, if there was no frequency shift involved you would not be able to perceive the image, other than as an array of numbers. To facilitate your consumption of the data it has to be frequency shifted and the easiest way to do this is to map the IR intensity to a ra…

Thanks, but how is the sausage made then? Guess, that’s my main question. I get that the aquired data needs to be transformed in a way so we get an image that depicts a reality we can visually process. I honestly thought there’s some tools in Nasa’s imaging group that, based on scientific rules, pumps out an image that is correct - seeing Photoshop in use left me wonder… I get that the investment needs to be “sold” t…

Because light red shifts over time/expansion, you could color these towards blue until they cover parts of the human vision space to what they would look like on earth a billion years ago or so.

In that case you could render the image differently depending on how many millions of years in the past you were interested in.

I.e these used to be human “visible” on earth, but eventually their colors shifted beyond what we can perceive with our eyes.

Re: James Webb first images – complete set of high resolution shots now live

#295

Post by randyrand »

bottled_poe wrote: post #101
whiteboardr wrote: post #77

Watching the livestream i was more than surprised, that color correction actually happens in Photoshop. Also, there seem to be multiple layer-masks involved for specific regions and objects. I get that you can shift and composite color, based on hue, apply filters etc, but: Photoshop? Curious if anyone can explain, that what we see is actual science or some touched up version of objects in our universe. p.s.: What st…

I’m confused.. why would we expect some other image processing software to be better than Photoshop - a software package which has been the top of its class for ~30 years?

Because photoshop it not open source, not verifiable, and not documented on a scientific level about how its filters behave.

Re: James Webb first images – complete set of high resolution shots now live

#296

Post by 87tau »

AlexFielder wrote: post #248

Serious question: How do I explain this to my nine year old?

Unsure what you want to explain or what your nine year old already knows, but generally I would start by explaining to him/her/them that these are pictures of very far away and enormous objects taken from a telescope that is located further away than the moon.

The telescope takes pictures in a different frequency band, like an infrared camera. These pictures are then color mapped to blue, green yellow and other colors that you normally see because just black and white image are boring to look at.

Re: James Webb first images – complete set of high resolution shots now live

#297

Post by dmead »

willis936 wrote: post #147
dmead wrote: post #133

Earlier quoted context omitted.

amateur astronomer here. ( https://www.instagram.com/mead_observatory/ ) 1. photoshop is really good at composing different (spectral) layers together. There is alternatives to this like pixinight that are more geared toward deep sky astronomy work but I'm sure it's easier to hire people that can just take a Photoshop class. there are many layers/masks involved for different filters. the filters accept or reject cert…

Thanks for 3. Without the explanation it really did come off as doctoring data to be more artistic.

But they are doctoring it to make it more artistic/presentable. I have no doubt that real astronomy presentations/papers want to see the undoctored data at some point.

Did you mean you thought they were adjusting the content and not just fixing noise?

Re: James Webb first images – complete set of high resolution shots now live

#298

Post by dguest »

wthomp wrote: post #255
dguest wrote: post #159

Earlier quoted context omitted.

Everything will be public eventually. There's a bit on the data policy on wikipedia [1] but basically the operations costs are funded (in part) by people paying for telescope time. The project that is currently paying for the telescope gets exclusive access for a 1 year "embargo" period, after which the data becomes public. [1]: https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Gro...

Small correction, no one will be able to pay for time on JWST. But if you put in a proposal for time and it's accepted, they will pay you . That's to make sure there is sufficient funds available to properly make use of the data you proposed for.

Actually that's sort of a large correction, thanks for pointing that out. Isn't it a bit of an inversion of the norm in astrophysics? I'd thought many grants included money for telescope time.

Re: James Webb first images – complete set of high resolution shots now live

#299

Post by dmead »

buildbot wrote: post #164
dmead wrote: post #133

Earlier quoted context omitted.

amateur astronomer here. ( https://www.instagram.com/mead_observatory/ ) 1. photoshop is really good at composing different (spectral) layers together. There is alternatives to this like pixinight that are more geared toward deep sky astronomy work but I'm sure it's easier to hire people that can just take a Photoshop class. there are many layers/masks involved for different filters. the filters accept or reject cert…

To point 3, they are absolutely keeping many, many maps of the pixels and dark current for all of their sensors - this is a good picture of the process for a standard astronomical CCD: https://cdn.nightskypix.com/wp-content/uploads/2020/06/calib...

which reminds me, i need to update my dark library and get a light for flats.
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