“Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.” -D.A....R.I.P.
James Webb first images – complete set of high resolution shots now live
371–380 of 410 posts
Re: James Webb first images – complete set of high resolution shots now live
#372Direct 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?
I am wondering what size of the "cosmic dust" are. It looks like the size of stars but without emitting light?
Re: James Webb first images – complete set of high resolution shots now live
#373Earlier quoted context omitted.
> “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"
Visible light looks like this: https://www.adamblockphotos.com/ngc-3372-carina-nebula.html
But that's with a telescope and long exposure & image stacking. But still in RGB as humans would see it.
I guess there would be a point that if you were not so far away, but still far enough away - it would light up the sky. This is emission nebula after all.
BUt if you were in it, it would be so diffuse that you wouldn't know it... perhaps a weird glow if you were near some of the forming stars.
Re: James Webb first images – complete set of high resolution shots now live
#374Earlier quoted context omitted.
You are obviously missing the point. They want to know what it would look like to a human observer.
It's the wrong question to ask because a 'human observer' would see absolutely nothing. The age of the objects you are looking at is such that you are looking into the past not at something the is still there in the present, so if we were to transport you there you would not recognize the various objects in visible light at all, too much time has passed. At this level 'distance' = 'time'.
> if we were to transport you there you would not recognize the various objects in visible light at all, too much time has passed.
I think this is an old interpretation of the speed of light and spacetime, since it describes travelling very far through space and also time. So it's more of a statement about the realities of space travel than what it would be like to be there now.
As you said, distance = time, so saying that too much time has passed is the same as saying that it's too distant to see, which is kind of beside the point.
I would say that what we see in the pictures really is the nebula as it exists now, but if you tried to travel there at near the speed of light, your speed through time would increase so much that you would see it rapidly change.
The real question is, what would you see if you were there now (at the time during which the shape of the nebula matches the photo).
Re: James Webb first images – complete set of high resolution shots now live
#375Earlier quoted context omitted.
Thanks for the direct links! > Webb's First Deep Field (NIRCam Image) Is this image distorted in any way at all? It feels like the galaxies are somehow oriented around a center spot. Not all of them, but enough to give the image a distorted feeling. Probably it's just my mind pattern matching against something that doesn't really exist.
Something missing from this discussion that's worth pointing out: This image shows profound "gravitational lensing", which you know. But what you might not know is that is precisely _why_ they chose to photograph it. This galaxy cluster (SMACS 0723) may be the most well known and powerful gravitational lens we have observed. The galaxies shown distorted around the edges are actually behind the lens, but are magnified…
The mind blowing part is that many of those smeared galaxies are the same galaxy just "smeared" around the curvature of space so it shows up in multiple places as we perceive it since its been warped by the gravitational mass/dark matter so strongly.
Re: James Webb first images – complete set of high resolution shots now live
#376Earlier quoted context omitted.
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.
> open source
This is not a criterion of high quality software.
Re: James Webb first images – complete set of high resolution shots now live
#377Earlier quoted context omitted.
So, would that mean that the gravitational lensing over how-ever-many-light-years is ALSO coupled with the convex/cave aspect of the pico-adjusting of the JWT 'lens' such that even our JWT's pico-adjustments affect the NORMAL of the photons to the image? Can this be adjusted for? Wouldnt the pico-arc of the overall array affect the image output due to the distances involved such that we receive "false gravitational l…
I'm convinced we are receiving "Wobbly Photons" Meaning that no matter waht, when we speak of gravitational lenses, we could, usting JWST account for the "wobble" of a photon, nased on the accurate knowledge of where a body was, via measuring through multiples of JSWT observations... (ideally through actually multiple JWSTs, in differnt locations) The idea being that if we can triangulate a more precice location betw…
We already calculated the gravity and mapped it out. Here is a paper on some of the research: https://www.kiss.caltech.edu/papers/darkmatter/papers/the_da...
What i think is pretty cool is that the gravity lens actually allowed hubble to see galaxies it may have not ever seen had there not been a gravity lens and now that we have JWST we see many more distant galaxies (and more of the same galaxy reflected in more positions)
Re: James Webb first images – complete set of high resolution shots now live
#378Watching 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 use PixInsight myself, but you can do a lot on photoshop and a lot of people will take the output of PixInsight to touch up in photoshop.
Modern sensors are amazingly low noise. 10 years ago, I used to have to calibrate out darks, bias and flats just to remove my sensor noise. Now with modern CMOS sensors, people still do that but it isn't as necessary and you can overcome much of the sensor noise by capturing enough data - and that's where JWST just dominates. THere is nothing impeeding the data causing noise.
Shot noise is easily removed by integration, Read noise on modern sensors is almost non existent and easily calibrated out, dark current is extremely low, bias, hot and cold pixels are all things that can be removed with calibration and integration and with space telescopes cosmic rays are probably the most annoying thing but if you stack enough images they integrate right out.
But back to photoshop, the final images are just publishing art. I use pixinsight myself for all the heavy lifting, pixel math, integration and calibration but sometimes go out to photoshop for cleanup - especially for web/print.
Re: James Webb first images – complete set of high resolution shots now live
#379Earlier quoted context omitted.
My understanding is that the IR here is used to see "through" the "smoke", so you can see more details that would normally be obstructed. A good way to see this is comparing it to Hubble [1], a lot of the extra detail you see is thanks to IR letting you see the stars behind. [1] https://johnedchristensen.github.io/WebbCompare/
Understood! What I was asking is: Is the target's normally-visible light redshifted into the same bands that JWST is measuring, higher? or lower frequency? That doesn't have anything to do with why JWST uses IR.
Ok, disclaimer: I am not an astronomer and this might all be rubbish. I suspect I'm neglecting relativistic effects that might be important, for example.
The NIRCAM instrument on JWST has a wavelength range of about 600 - 5000nm [1]. The human eye is sensitive to around 380nm - 700nm.
To shift blue light (380nm) down to the upper frequency range of NIRCAM (600nm) requires a redshift of:
z = Δλ / λ0 = 0.58
This is related to the velocity of the object by:
z = v / c
and the velocity is related to distance (approximately) by the Hubble constant (H0 ~ 71 km/s / Mpc):
d = v/ H0
So we can rearrange and solve for distance to get:
d = z c / H0 = 8 billion light years.
The southern ring nebula is more like 2000 light years from us, so not even vaguely far enough that NIRCAM would see "originally-visible" light. The deep field image might actually be far enough... the faintest galaxies there might be something like 12 billion light years away [2].
[1] https://www.stsci.edu/jwst/instrumentation [2] https://www.nasa.gov/content/discoveries-hubbles-deep-fields
Re: James Webb first images – complete set of high resolution shots now live
#380https://www.stsci.edu/files/live/sites/www/files/home/jwst/d...>
The science performance report of JWST is a fascinating read. Some of the highlights that sent me down a rabbit-hole
- On Predicted lifetime of consumables - Before launch, JWST was required to carry propellant for at least 10.5 years of mission lifetime. Now that JWST is in orbit around L2, it is clear that the remaining propellant will last for more than 20 years of mission lifetime.
- On Orbit - Orbit around L2 is maintained through regular station-keeping burns, which are scheduled every three weeks
- On observatory lifetime - At present, the largest source of uncertainty is long term effects of micrometeoroid impacts that slowly degrade the primary mirror.
- On Other spacecraft performance - JWST is now generating 1.5 kW to match the power load, with a capability of > 2 kW
- On Fault management - Of the 344 single point failures at launch, almost all of them related to deployments, only 49 remain; these are common to most science missions (for example, only one set of propellant tanks, only one high gain antenna)
The section on "Pointing and guiding" which mentions how complex sub-systems interact to achieve "line-of-sight stabilization" and how its not possible to test those systems together in an end-to-end fashion on the ground is interesting.