Author Topic: NASA - James Webb Space Telescope - Discussion Thread 2  (Read 340760 times)

Offline Welsh Dragon

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1120 on: 07/17/2022 07:16 am »
1. They're not going to hold a press conference for every image. New images will show up at the Mikulski Archive for Space Telescopes.
What makes you deduce at the Mikulski Archive for Space Telescopes will be used to air new images of the deep cosmos taken by the James Webb Space Telescope? I'd assume some JWST images of the cosmos could be placed in confidential records.

I didn't deduce that, that's the published policy of the JWST team.
- all images and other observation data will be published.
- for images in the General Observer program (i.e. observation requests from astronomers) there will be a period of exclusive access, usually 6-12 months. These images will still be stored on MAST but during the exclusive access period, you need to log in to access them; access is limited to the requesting astronomer. After the exclusive access period everyone will have access to the images.
6-12 months that seems a bit excessive. Thatís the sort of thing that should be under constant review.

AFAIK, 6 months is standard, but astronomers can ask for a longer period of up to 12.
12 months withholding publicly paid for data from the scientific community at large I hope thatís the exception rather than the rule.
For most scientific work (publicly funded or not) you will never see the raw data. You should be happy with only 12 months.

Offline ttle2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1121 on: 07/17/2022 10:05 am »
Very standard, though it is waived for some stuff e.g. the TESS and Kepler data went public immediately via MAST, though obviously some GO programmes were proprietary.

--- Tony

Recently the trend has been towards reducing proprietary periods and if I recall correctly, for JWST the default/available exclusive access periods are reviewed for each proposal cycle. I doubt they are going to be removed completely for all types for programs (particularly GO) anytime soon, though.

I think many people complaining about the exclusive access don't understand how much work it takes to write a GO proposal for JWST (or any other top instrument) that has any chance of getting selected. The situation is very different from surveys and planetary probes, where one doesn't write a proposal to observe some specific target.

If the data were available immediately, someone else scoop the result, and the original proposers who did a lot of work would be left with nothing (in the worst case). Of course, in many cases the GO proposers are the only ones with the specific expertise to analyse the data so that there is little chance of getting scooped and in such cases they may choose to waive the exclusive access, but in others someone else could write at least a quick-and-dirty flag-planting paper to claim priority.
« Last Edit: 07/17/2022 10:05 am by ttle2 »

Offline eeergo

Example of a public repository of commissioning images (from MIRI, in this case), with commentary:

https://github.com/merope82/JWIms

Found it through Twitter.
-DaviD-

Offline Blackstar

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1123 on: 07/17/2022 09:15 pm »
I think many people complaining about the exclusive access don't understand how much work it takes to write a GO proposal for JWST (or any other top instrument) that has any chance of getting selected.

But why should not understanding how something works prevent somebody from complaining about it? Isn't that the basis of the internet?

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1124 on: 07/17/2022 09:29 pm »
I think many people complaining about the exclusive access don't understand how much work it takes to write a GO proposal for JWST (or any other top instrument) that has any chance of getting selected.

But why should not understanding how something works prevent somebody from complaining about it? Isn't that the basis of the internet?
Only for the terminally cynical.

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1125 on: 07/17/2022 09:31 pm »
How far back is the James Webb able to see?
with Dr. Klaus Pontoppidan


Offline Don2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1126 on: 07/18/2022 10:44 pm »
This is a quick comparison of M74 images. M74 is an archetypal spiral galaxy. The stars disappear in the new mid-infrared JWST image and the spiral density wave structure in the dust shows much more detail. Also, the 'fog' in the center disappears, and the central region becomes much more visible. I wonder if the bright dot in the center is an accretion disc surrounding a black hole?

Hubble seems to be higher resolution because it is taken at shorter wavelength. Also, it shows glowing pink regions of hydrogen gas surrounding regions of active star formation. That pink light is 656 nm, so I think it would just be within the range of NIRCam on JWST.


Cropped from JWST image from Twitter (via eergo on the update thread):  MIRI F770W / F1000W / F1130W by PHANGS-JWST
https://twitter.com/gbrammer/status/1548958244646928385

HST image cropped and contrast enhanced from: https://hubblesite.org/contents/media/images/2007/41/2210-Image.html
« Last Edit: 07/18/2022 10:50 pm by Don2 »

Offline ttle2

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1127 on: 07/19/2022 08:04 am »
Hubble seems to be higher resolution because it is taken at shorter wavelength. Also, it shows glowing pink regions of hydrogen gas surrounding regions of active star formation. That pink light is 656 nm, so I think it would just be within the range of NIRCam on JWST.

H-alpha is barely inside the shortest wavelength NIRCam filter F070W but since it's a broadband filter, it wouldn't pick up HII regions that well.

NIRCam filters: https://jwst-docs.stsci.edu/jwst-near-infrared-camera/nircam-instrumentation/nircam-filters
MIRI filters: https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument/miri-instrumentation/miri-filters-and-dispersers

Offline leovinus

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1128 on: 07/19/2022 09:14 pm »
1. They're not going to hold a press conference for every image. New images will show up at the Mikulski Archive for Space Telescopes.
Which is here  https://mast.stsci.edu/portal_jwst/Mashup/Clients/Mast/Portal.html

For example, fill the top-left box "and enter target:" with "TRAPPIST-1", and select on the left "Mission" as "JWST" and you get the scheduled images from proposal we summarized here earlier in thread. No images yet.
FYI, based on a quick look this morning, some data from two JWST TRAPPIST-1 proposals (2589, 2420) and observations of last few days, is downloadable. Interpretation is another matter ;)

Offline leovinus

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1129 on: 07/20/2022 07:09 pm »
An attempt to compare the "smudge" between the two stars. Left, JWST today, right same image as in earlier post. In today's JWST image you can actually see that this is a distorted galaxy. Mindblowing!
A first attempt on Arxiv to unscramble the lensed galaxies. The quoted smudge from above is on page 3 of article.

Unscrambling the lensed galaxies in JWST images behind SMACS0723
https://arxiv.org/pdf/2207.07102.pdf

Quote
The first deep field images from the James Webb Space Telescope (JWST) of the galaxy cluster SMACS J0723.3-7327 reveal a wealth of new lensed images at uncharted infrared wavelengths, with unprecedented depth and resolution. Here we securely identify 14 new sets of multiply imaged galaxies totalling 42 images, adding to the five sets of bright and multiply-imaged galaxies already known from Hubble data. ...

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1130 on: 07/21/2022 06:24 am »
Pretty decent article covering this news, and Iíll give the writer a bonus point for getting a WWE reference in there.

https://www.cnet.com/science/space/did-the-webb-space-telescope-find-the-oldest-galaxy-ever-seen-its-complicated/

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1131 on: 07/21/2022 07:44 am »
Has anyone else noticed the scaremongering way that the report on the micrometeoroid hit on the telescope has been reported. The way a number of news article have spun that report has been to suggest that the JWST is somehow so badly damaged that it is impaired from doing its job. At first I thought it was a one off but now I’ve seen more and more articles with the same spin.

This article actually looks at this phenomenon.

https://mashable.com/article/james-webb-space-telescope-meteoroid-damage-nasa
« Last Edit: 07/21/2022 07:46 am by Star One »

Offline webdan

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1132 on: 07/21/2022 10:26 am »
Yep, news ain't what it used to be. Now comes with extended analysis and unlimited ads.

Just like that first ding on your new car. You'll get used to it.

Offline bkellysky

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1133 on: 07/21/2022 10:51 am »
Has anyone else noticed the scaremongering way that the report on the micrometeoroid hit on the telescope has been reported. The way a number of news article have spun that report has been to suggest that the JWST is somehow so badly damaged that it is impaired from doing its job. At first I thought it was a one off but now Iíve seen more and more articles with the same spin.

This article actually looks at this phenomenon.

https://mashable.com/article/james-webb-space-telescope-meteoroid-damage-nasa
Yes, I've noticed many new articles about the micrometeoroid hit. The headlines accompanying the latest articles make it sound like there is new data showing the effects of the hit are worse than expected, but the articles themselves are almost word-for-word from the earlier write-ups. So, nothing new since the original reports. As far as I've seen.

Offline Hobbes-22

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1134 on: 07/21/2022 12:35 pm »
There is new data: the commissioning report is out, and it specifies what the distortion of the mirror is (1 um around the impact area), and how much it affects the images (wavefront error went from 50 to 59 nm).

https://www.stsci.edu/files/live/sites/www/files/home/jwst/documentation/_documents/jwst-science-performance-report.pdf
« Last Edit: 07/21/2022 12:41 pm by Hobbes-22 »

Offline bkellysky

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1135 on: 07/21/2022 02:21 pm »
There is new data: the commissioning report is out, and it specifies what the distortion of the mirror is (1 um around the impact area), and how much it affects the images (wavefront error went from 50 to 59 nm).

https://www.stsci.edu/files/live/sites/www/files/home/jwst/documentation/_documents/jwst-science-performance-report.pdf
Thank you for including the link to the paper published July 12th, the day the first set of photos were released.

Offline Star One

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1136 on: 07/21/2022 03:01 pm »
Has anyone else noticed the scaremongering way that the report on the micrometeoroid hit on the telescope has been reported. The way a number of news article have spun that report has been to suggest that the JWST is somehow so badly damaged that it is impaired from doing its job. At first I thought it was a one off but now Iíve seen more and more articles with the same spin.

This article actually looks at this phenomenon.

https://mashable.com/article/james-webb-space-telescope-meteoroid-damage-nasa
Yes, I've noticed many new articles about the micrometeoroid hit. The headlines accompanying the latest articles make it sound like there is new data showing the effects of the hit are worse than expected, but the articles themselves are almost word-for-word from the earlier write-ups. So, nothing new since the original reports. As far as I've seen.
Whatís depressing but not surprising is it feels like the UK media have been far more guilty of this than the US media, but perhaps I am more aware of it being in the UK.

Offline eeergo

There is new data: the commissioning report is out, and it specifies what the distortion of the mirror is (1 um around the impact area), and how much it affects the images (wavefront error went from 50 to 59 nm).

https://www.stsci.edu/files/live/sites/www/files/home/jwst/documentation/_documents/jwst-science-performance-report.pdf

Just noting these findings were already discussed in the Update thread more than a week ago:

Quote
- The MMOD hit on the C3 mirror detected in May was relatively humongous has prompted worries: it can be a freak incident, or it can result from mismodelling of the micrometeoroid environment in L2: the single micrometeorite impact that occurred between 22ó24 May 2022 UT exceeded prelaunch expectations of damage for a single micrometeoroid: predicted that on average each segment would receive a cumulative total of 16 nm added wavefront error over six years. The May impact resulted in one segment receiving more than 10 times that average in a single event, and raised the mirror's wavefront error from 56 to 280 nm, subsequently corrected to 178 nm, which then translates to an integrated impact to the observatory of 9 nm, degrading the wavefront error from 50 to 59 nm. [...] The best achieved telescope wavefronts at the completion of alignment were as low as 50 nm rms; the May 2022 micrometeoroid impact on segment C3 subsequently raised the high-order uncorrectable WFE term enough that the floor is now 59 nm rms. See first attached image. Other six MMOD impacts were detected, in accordance with micrometeoroid impact preflight modeling (as opposed to the "big one") but their impact was negligible

It's illustrative to read the whole sections in the report discussing the impact. Let's say the performance hit is manageable for now (59 nm WFE is the integrated impact, but it has tripled in C3), but it's not negligible, and raises fears this was not just "bad luck right at the beginning" - what if instead these events turn out to be more frequent than expected? There's no way to know until more time passes.
-DaviD-

Offline Hobbes-22

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1138 on: 07/21/2022 03:30 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.

Offline edzieba

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Re: NASA - James Webb Space Telescope - Discussion Thread 2
« Reply #1139 on: 07/21/2022 04:25 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.

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