James Webb Telescope

acbytesla said:
So so cool. :thumbsup:

I was skeptical that the telescope was going to work. I was sure that something was going to go wrong. I remember too well when the Hubble was a very expensive joke.

BTW: Have you turned in an application for time on it?
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I wouldn't even know where to begin!
 
smartcooky said:
I wouldn't even know where to begin!
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I could tell you where to begin. But that is as far as it would likely get. That is the part of the Hubble and JWST I find so cool. Anyone and I mean anyone from anywhere can get time on them. You just have to propose an idea interesting enough. The committees that run them decide solely on the proposal and not on who is doing the proposal. It's done totally blind. Dr. Becky explained how this is done in one of her videos.
 
3point14 said:
Here you go:

https://jwst-docs.stsci.edu/getting-started-with-jwst-proposing


Let us know how you get on :D


(How much of the JWST time is alrady allocated? Can one still submit a proposal? I have no idea, and I couldn't find it on that link)
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I'm pretty sure the answer is yes. But not for the present year. Time has been allotted.

I think they basically decide year by year. Each years proposals are required by a certain date of that year.

There are a lot of factors including the practicality of how much adjusting is required to point the JWST at a particular astronomical object. So two proposals that want to observe two objects close to each other in direction are done following each other as opposed to pointing it in a radically different direction on each proposal.
 
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That would suck if you came up with a proposal, only to be told that the region in question had been last year's focus, and the scope would be pointing somewhere else this year.

Or maybe it would be great, if the data you were interested in had come flowing in last year while the scope was looking that way already.
 
theprestige said:
That would suck if you came up with a proposal, only to be told that the region in question had been last year's focus, and the scope would be pointing somewhere else this year.

Or maybe it would be great, if the data you were interested in had come flowing in last year while the scope was looking that way already.
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A lot goes into moving the JWST including fuel. But I don't think it works the way you imagine. They don't assign a specific area of the universe to evaluate. They evaluate the proposals and then make a calendar for the year taking into account the adjustments required.

Also since the proposal evaluation is blind, they are unlikely to communicate to you the reason your proposal isn't accepted. You are likely faced with resubmitting your proposal year after year and not knowing why it isn't accepted.
 
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Due to its position at the L2 point, it always has to be facing away from the sun and the earth, so at any given moment it will only have about half of the sky that it can look at. Over the course of a year it will make a complete orbit of the sun of course, so they probably schedule what to look at accordingly.

For myself, although extremely distant objects like the first stars and early galaxies are interesting, I'm actually more interested in finding out about exoplanets in our own neighborhood of the Milky Way that might harbor life. We're never going to go to any other galaxy, realistically, because they are just too far away.
 
Puppycow said:
Due to its position at the L2 point, it always has to be facing away from the sun and the earth, so at any given moment it will only have about half of the sky that it can look at. Over the course of a year it will make a complete orbit of the sun of course, so they probably schedule what to look at accordingly.
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Not quite right. It actually cannot face directly away from the sun because that would expose the back of the mirror structure and instrument packages to direct sunlight... game over!

It has to face within a few degrees of 90°, actually between 85° and 135°, of the Sun/Earth position.


ETA:

JWST%20pointing.png
 
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smartcooky said:
Not quite right.

It actually cannot face away from the sun because that would expose the back of the mirror structure and instrument packages to direct sunlight... game over!

Ity has to face within a few degrees of 90°, actually between 85° and 135°, of the Sun/Earth position.


ETA:

[qimg]https://www.dropbox.com/s/o4oovyqkrze99fg/JWST%20pointing.png?raw=1[/qimg]
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Thanks. So over the course of a full orbit of the sun it will eventually be able to point in any direction away from the sun. It won't ever be able to look toward the earth, sun or inner planets though.
 
Puppycow said:
Thanks. So over the course of a full orbit of the sun it will eventually be able to point in any direction away from the sun. It won't ever be able to look toward the earth, sun or inner planets though.
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Yes, it can see things in the orbital plane of the Earth but only while the telescope is pointing approximately parallel to a tangent to the Earth's orbit.
 
Puppycow said:
Thanks. So over the course of a full orbit of the sun it will eventually be able to point in any direction away from the sun. It won't ever be able to look toward the earth, sun or inner planets though.
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Looking towards the Sun is not a good idea! Everything will get washed out by its glare. The CMB satellites were at the L2 point, and looked away from any contaminating radiation from the solar system, as well as being shielded from such radiation.
 
"..“We spent years practicing...running through the commands and the checks that we did on MIRI [...] When the test data rolled in, I was ecstatic to see it looked exactly as expected and that we have a healthy instrument.” - Mike Ressler,
@NASAJPL’s MIRI project scientist.."​

Clever people.
 
ohms said:
NASA reporting that Miri has cooled down to its operating temperature and is ready for calibration

https://twitter.com/NASAWebb/status/1514273886510137360
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And with that, Step 7: Final Correction has commenced...

"After applying the Field of View correction, the key thing left to address is the removal of any small, residual positioning errors in the primary mirror segments. We measure and make corrections using the Fine Phasing process (Step 5). We will do a final check of the image quality across each of the science instruments; once this is verified, the wavefront sensing and controls process will be complete.

As we go through the seven steps, we may find that we need to iterate earlier steps as well. The process is flexible and modular to allow for iteration. After roughly three months of aligning the telescope, we will be ready to proceed to commissioning the instruments."
 
smartcooky said:
And with that, Step 7: Final Correction has commenced...

"After applying the Field of View correction, the key thing left to address is the removal of any small, residual positioning errors in the primary mirror segments. We measure and make corrections using the Fine Phasing process (Step 5). We will do a final check of the image quality across each of the science instruments; once this is verified, the wavefront sensing and controls process will be complete.

As we go through the seven steps, we may find that we need to iterate earlier steps as well. The process is flexible and modular to allow for iteration. After roughly three months of aligning the telescope, we will be ready to proceed to commissioning the instruments."
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I have to wonder if they are using Engineer Scotty estimating. You know. Where he says it will be done in three months when they can actually get it done in far less.:D
 
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