Author Topic: NASA - James Webb Space Telescope - Discussion Thread 2  (Read 340779 times)

Offline ttle2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1140 on: 07/21/2022 06:27 pm »
We've been operating spacecraft at L2 (including one with an exposed large mirror) for several decades now. That tells us impacts of this size are rare, or we'd have noticed them before.
We haven't been operating 6.5m wide sensitive particle impact detectors in L2, though. Or particle impact detectors of any size, beyond measurements of aggregate drop in solar array power assumed to be from micrometeoroid impact (current L2 telescopes other than JWST are enclosed). There are models of expected micrometeoroid population, but limited direct measurements.

Herschel's mirror wasn't enclosed and got a good number of square metre years at L2, but I doubt even a micrometeoroid of this size would have caused detectable changes in image quality. At the wavelengths Herschel operated, surface accuracy requirements are much lower.

I can't think of any other at least moderately large UV-optical-NIR mirrors at L2 than Gaia, but its I think its mirrors are protected by the spacecraft structure.
« Last Edit: 07/21/2022 06:28 pm by ttle2 »

Offline catfry

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1141 on: 07/22/2022 09:09 am »
Gaia at L2 is able to detect momentum changes to the degree that it has detected being hit by micrometorids. Since it is a astrometry mission it needs to know at all times where it is pointing, to unfathomable precision.
Here's some discussion of one hit with a calculated mass of 48 micrograms. unfortunately I don't know that there is any published information about hit rates for that telescope.
« Last Edit: 07/22/2022 09:25 am by catfry »

Offline catfry

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1142 on: 07/23/2022 11:22 am »
To further add to the post above, no actual paper or data, but there is an article describing the method, and a promise of a future publication by a phd student, Marie-Liis Aru of ESO, using data from Gaia to characterize the micrometeoroid environment at L2. She's got a twitter https://twitter.com/bymarieliis:

https://space-travel.blog/gaia-rocks-96ec6d70ae90

Quote
The data set comprises millions of peaks and valleys that correspond to tiny deviations in the spacecraft’s angular velocity. These extrema reflect either 1) normal operation of the system at the lowest deviation level (the noise floor), 2) spacecraft manoeuvers, 3) unexplained events, or 4) micrometeoroid impacts. As the first part of the project, I classified these events and set out to find ways to distinguish small-amplitude impacts embedded in the noise floor of normal operation. This being akin to a needle in a haystack problem, it was necessary to study the time profiles caused by the micrometeoroid impacts very carefully, describe them with statistical parameters, and apply these parameters to find small-amplitude impacts embedded in the noise floor. Finding impact signatures in the data provides a distribution of the angular velocity change values; however, these values do not directly correspond to the size of the particles. The AOCS reaction depends on impact location, mass, and velocity.

Online FutureSpaceTourist

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1143 on: 07/23/2022 04:03 pm »


Quote
What We're Seeing Through NASA's James Webb Space Telescope

21 Jul
2022
A ~3,000,000x zoom from Earth into Webb's First Deep Field and beyond. Best viewed full screen, and with sound. More on the math and making of: claybavor.com/blog/webbs-deep-field

Image credits:

Night Sky – Clay Bavor
Moon and M52 Cluster – Adobe Stock / Infinitalavita
Webb’s First Deep Field – NASA, ESA, CSA, and STScI
Spiral Galaxy NGC 691 – SA/Hubble & NASA, A. Riess et al.
Milky Way Galaxy – Jesse Levinson

Offline Don2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1144 on: 07/26/2022 12:13 am »
I had a go at processing an image from the MAST archive. IC 5332 is a spiral galaxy about 30 million light years away.


Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1145 on: 07/27/2022 10:39 am »
I wonder if there’s any way of importing these to the UK without being charged a hefty fee.

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The James Webb Space Telescope has already traveled 1 million miles through space. Soon, the next-generation telescope will be making its way through the U.S. Postal Service.

The Postal Service announced Tuesday that the James Webb Space Telescope will be featured on new stamps becoming available September 8 (pre-orders begin Aug. 8). The image features the telescope's 18 gold-coated segments, which form a 21-foot mirror lens.

The new Forever stamps – priced at 60 cents, a pane of 20 is $12 – will feature the $10 billion scientific marvel, which sent back images earlier this month that wowed the scientific community and laypersons alike. The telescope, which was launched Dec. 25, 2021, is a joint project involving NASA, The Canadian Space Agency and the European Space Agency.

https://eu.usatoday.com/story/news/nation/2022/07/26/james-webb-space-telescope-stamp-us-postal-service/10155892002/
« Last Edit: 07/27/2022 10:41 am by Star One »

Offline Oersted

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1146 on: 07/27/2022 08:47 pm »
How about having a US-based friend ... mail you some?

Offline leovinus

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1147 on: 07/27/2022 09:32 pm »
A new preprint describes an even higher redshift, z=16.7, galaxy candidate: https://arxiv.org/abs/2207.12356

Now claims of z~20 at First Batch of Candidate Galaxies at Redshifts 11 to 20 Revealed by the James Webb Space Telescope Early Release Observations.
https://arxiv.org/pdf/2207.11558.pdf

It feels to me like there is a gold rush style discovery competition going with JWST. My daily Arxiv search keeps flagging up new papers with ever higher redshift. While these preprints are not peer reviewed yet, it looks like there are some really ancient galaxies in that one picture. And that is only the first deeper picture! z~20 is about 70 tot 80 million years after the BigBang, nuts.

The Quanta article Two Weeks In, the Webb Space Telescope Is Reshaping Astronomy is a lighter read than Arxiv but this nugget confirms the gold rush.
Quote
Three days later, just minutes before the daily deadline on arxiv.org, the server where scientists can upload early versions of papers, the team submitted their research. They missed out on being first by 13 seconds, “which was pretty funny,” said Pascale.

Can't wait for more papers and discoveries. Confirmation and cross checks would be good. And an early TRAPPIST analysis would be icing on the cake :)
« Last Edit: 07/27/2022 09:34 pm by leovinus »

Offline Don2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1148 on: 07/29/2022 01:52 am »
Using data from the MAST archive, this is NGC 7496. This is a barred spiral galaxy located about 24 million light years from Earth.

Offline Don2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1149 on: 07/29/2022 02:13 am »
WR 140 is a dust producing binary star system containing a Wolf-Rayet and a hot blue star. The rings in the picture are probably concentric shells of dust. The JWST image is a revolutionary improvement over previous images. Processed by me from data in the MAST archive

https://www.roe.ac.uk/~pmw/Wr140int.htm
Animation of system: https://webbtelescope.org/contents/media/videos/2020/57/1298-Video


« Last Edit: 07/29/2022 02:14 am by Don2 »

Offline Oersted

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1150 on: 07/29/2022 08:46 pm »
Oh! - Am I understanding this right, that each of those concentric not-quite-circular shapes are a tail of dust thrown out by an orbit of the two stars? And that the rings are then expanding outwards?   

Offline Hungry4info3

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1151 on: 07/30/2022 12:43 am »
That's my understanding as well.

Offline Don2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1152 on: 07/30/2022 08:49 am »
Oh! - Am I understanding this right, that each of those concentric not-quite-circular shapes are a tail of dust thrown out by an orbit of the two stars? And that the rings are then expanding outwards?

I think that is what is happening. They must be concentric rings rather than concentric shells of dust as I said earlier. The animation I linked to doesn't really show a full ring of dust being ejected, so that model may have to be adjusted.

Offline Don2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1153 on: 07/30/2022 08:54 am »
There is some Jupiter data now in the archive, but I am finding it difficult to work with. One problem is that the planet rotates, so features move between different images. This image, taken at 1.5 microns, gives an idea of the resolution available.
« Last Edit: 07/30/2022 09:00 am by Don2 »

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1154 on: 07/30/2022 09:33 am »
When is JWST scheduled to observe the Proxima system?

Offline Hobbes-22

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1155 on: 07/30/2022 10:22 am »
When is JWST scheduled to observe the Proxima system?

I don't find any observations scheduled in the General Observer program for this year.
I did find an observation of Aplha Centauri A, scheduled for today. Program ID 01618.

you can put program IDs and get their schedule here. No option to search this by target. So I grabbed the GO Cycle 1 abstracts and got the program ID from there.
https://www.stsci.edu/jwst/science-execution/program-information.html

Offline Hog

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1156 on: 08/01/2022 12:58 am »
I gotta be lame and express my excitement to see a comparison with the Hubble Space Telescope's- Eagle Nebula's Pillars of creation.  Beautiful images that stir the soul.

attachment
1) 2014 "Pillars of Creation" 25th anniversary revisit-NASA HST
2) 2005 NASA Spitzer (IR)
3) 2019 amateur ground based 11" telescope courtesy-David Deyag-Israeli desert
Paul

Offline Redclaws

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1157 on: 08/01/2022 01:02 am »
There is some Jupiter data now in the archive, but I am finding it difficult to work with. One problem is that the planet rotates, so features move between different images. This image, taken at 1.5 microns, gives an idea of the resolution available.

Don, if you know: are those black dots(?) image artifacts?  Moons?  (Seems like too many/too uniform in size, but…)

Offline Don2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1158 on: 08/01/2022 05:49 am »
There is some Jupiter data now in the archive, but I am finding it difficult to work with. One problem is that the planet rotates, so features move between different images. This image, taken at 1.5 microns, gives an idea of the resolution available.

Don, if you know: are those black dots(?) image artifacts?  Moons?  (Seems like too many/too uniform in size, but…)

There are far too many to be moons. I think they are artifacts. Many of the images in the archive have much worse artifacts than that. There seems to be some problem with the processing.

Another issue is that there is a huge brightness range in the images. The central cloud belt, the Great Spot and the polar haze are VERY bright in the IR, and they have to be overexposed if you want to see any detail in the rest of the atmosphere.

I think it will take some time to work out how to produce attractive images from what they have. There is now quite a lot of data to work with, so somebody will figure it out. The people who process the Juno images have had years to figure out how to remove the haze and bring out the detail in the clouds.

There is also some Neptune data currently in the archive, but that is not publicly available yet.

Offline Hobbes-22

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1159 on: 08/01/2022 06:42 am »
It's a combination of dead pixels and variations in sensitivity. For NIRcam, they're documented here:
https://jwst-docs.stsci.edu/jwst-near-infrared-camera/nircam-performance/nircam-flat-fields

The black spots in this image are less sensitive than average, the green spots are dead pixels. The showcase images all used tiling to get rid of them.

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