The James Webb Space Telescope

collinsmark · Jul 7, 2022

pinball1970 said:

I wondered about the black hole Suns!

". In addition, the centers of bright stars appear black because they saturate Webb’s detectors, and the pointing of the telescope didn’t change over the exposures to capture the center from different pixels within the camera’s detectors"

Yeah, this is not an uncommon convention in astrophotography software (e.g., FITS viewers), particularly for use in quick-and-dirty viewing of the data. Saturated pixels are often displayed as black to let the astronomer know quickly (due to the inevitable high contrast) that saturation has occurred. It's not universal though -- it's just a convention -- and depends on the software. [It doesn't change the underlying data; rather it's just a matter of how the data is displayed.]

The same thing is often done on high-end terrestrial cameras too. So it's not limited to astronomy. Many high-end cameras (Nikon, Canon, etc.) will have a mode such that preview and display on the back of the camera will go black (or some predefined color [or pattern]) for regions where saturation occurs. It's a way of the camera telling the photographer, "Ah, hell. Looky-here, you've gone done blown the highlights again, you bastard."

Oldman too · Jul 8, 2022

A list of first image targets, compliments of NASA/JPL.
https://www.jpl.nasa.gov/news/nasa-shares-list-of-cosmic-targets-for-webb-telescopes-first-images?

Carina Nebula: The Carina Nebula is one of the largest and brightest nebulae in the sky, located approximately 7,600 light-years away in the southern constellation Carina. Nebulae are stellar nurseries where stars form. The Carina Nebula is home to many massive stars several times larger than the Sun.

WASP-96b (spectrum): WASP-96b is a giant planet outside our solar system, composed mainly of gas. The planet, located nearly 1,150 light-years from Earth, orbits its star every 3.4 days. It has about half the mass of Jupiter, and its discovery was announced in 2014.

Southern Ring Nebula: The Southern Ring, or “Eight-Burst” nebula, is a planetary nebula – an expanding cloud of gas surrounding a dying star. It is nearly half a light-year in diameter and is located approximately 2,000 light-years away from Earth.

Stephan’s Quintet: About 290 million light-years away, Stephan’s Quintet is located in the constellation Pegasus. It is notable for being the first compact galaxy group ever discovered in 1787. Four of the five galaxies within the quintet are locked in a cosmic dance of repeated close encounters.

SMACS 0723: Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a deep field view into both the extremely distant and intrinsically faint galaxy populations.

pinball1970 · Jul 11, 2022

What's this thing tonight? With Joe Biden? They are releasing one image?
@mfb @collinsmark @Oldman too
I posted a screen grab today and did not even notice the Biden date. On Random thoughts.

Oldman too · Jul 11, 2022

pinball1970 said:

What's this thing tonight? With Joe Biden? They are releasing one image?

I saw your screen grab, didn't notice the fine print about today though, thanks for pointing out the "reveal".

Devin-M · Jul 11, 2022

Does anyone know whether it would be possible to estimate the temperature of an object via a single narrowband observation? Suppose the F323N filter was used while NIRCam targeted an asteroid. Only 3.2 micron light can reach the imaging sensor. How would I derive the temperature of the asteroid from this single observation?

https://jwst-docs.stsci.edu/jwst-ne...cam-filters#NIRCamFilters-Filtertransmissions

pinball1970 · Jul 11, 2022

Devin-M said:

Does anyone know whether it would be possible to estimate the temperature of an object via a single narrowband observation? Suppose the F323N filter was used while NIRCam targeted an asteroid. Only 3.2 micron light can reach the imaging sensor. How would I derive the temperature of the asteroid from this single observation?

View attachment 304009

https://jwst-docs.stsci.edu/jwst-ne...cam-filters#NIRCamFilters-Filtertransmissions

I think they could have a good go at that

berkeman · Jul 11, 2022

pinball1970 said:

What's this thing tonight? With Joe Biden? They are releasing one image?
@mfb @collinsmark @Oldman too

Yeah, what the heck does Biden have to do with a NASA release? And the news articles say it would happen at 5:30PM US Eastern Time, which was an hour ago and no images anywhere that I can find so far...

Devin-M · Jul 11, 2022

https://www.nasa.gov/webbfirstimages

berkeman · Jul 11, 2022

Thank you very much, Devin. Is the color scheme that you showed in the plot above in your post #285 a standard for coloring the IR images from Webb?

phinds · Jul 11, 2022

I'm completely puzzled. The statement, on the NASA web site, about the age of the galaxies in the image says

The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago.

Given that the Hubble has imaged galaxies at about 13.4 billion years old, what's the big deal w/ 4.6 billion years old? The Webb image does not appear to me to be any more clear than the Hubble Deep Field,

berkeman · Jul 11, 2022

phinds said:

I'm completely puzzled. The statement, on the NASA web site, about the age of the galaxies in the image says

Given that the Hubble has imaged galaxies at about 13.4 billion years old, what's the big deal w/ 4.6 billion years old?

It looks like another metric/Imperial units conversion issue...

JLowe · Jul 11, 2022

I think SMACS is a bit more in the foreground, magnifying galaxies behind it that are apparently deeper and sharper than the Hubble deep field images.

dlgoff · Jul 11, 2022

berkeman said:

Yeah, what the heck does Biden have to do with a NASA release? And the news articles say it would happen at 5:30PM US Eastern Time, which was an hour ago and no images anywhere that I can find so far...

I saw this on the TV news this evening.

From: https://www.houstonchronicle.com/ne...ases-first-image-from-James-Webb-17297915.php

President Joe Biden released the first image from the James Webb Space Telescope on Monday, revealing what NASA called a "glimpse" into 13.5 billion years of cosmic history.

russ_watters · Jul 11, 2022

phinds said:

I'm completely puzzled. The statement, on the NASA web site, about the age of the galaxies in the image says

View attachment 304021
Given that the Hubble has imaged galaxies at about 13.4 billion years old, what's the big deal w/ 4.6 billion years old?

Typo substituting age of our sun for age of the universe?

The Webb image does not appear to me to be any more clear than the Hubble Deep Field

Here's a side-by-side with a Hubble photo of the same cluster:

fresh_42 · Jul 11, 2022

phinds said:

I'm completely puzzled. The statement, on the NASA web site, about the age of the galaxies in the image says

View attachment 304021
Given that the Hubble has imaged galaxies at about 13.4 billion years old, what's the big deal w/ 4.6 billion years old? The Webb image does not appear to me to be any more clear than the Hubble Deep Field,

Here is a comparison:
https://www.sciencealert.com/breaki...e-universe-ever-is-here-and-it-s-breathtaking

Hubble:

Webb:

fresh_42 · Jul 11, 2022

russ_watters said:

Typo substituting age of our sun for age of the universe?

Here's a side-by-side with a Hubble photo of the same cluster:

It is about what's behind the cluster.

Vanadium 50 · Jul 11, 2022

Be aware that the Webb pictures are in false color.

Devin-M · Jul 11, 2022

Jarvis323 · Jul 11, 2022

phinds said:

I'm completely puzzled. The statement, on the NASA web site, about the age of the galaxies in the image says

View attachment 304021
Given that the Hubble has imaged galaxies at about 13.4 billion years old, what's the big deal w/ 4.6 billion years old? The Webb image does not appear to me to be any more clear than the Hubble Deep Field,

berkeman said:

It looks like another metric/Imperial units conversion issue...

russ_watters said:

Typo substituting age of our sun for age of the universe?

4.6 billion years is the age of the light that the telescope collected, based on the distance, hence "as it appeared ...".

Filip Larsen · Jul 12, 2022

The Ars technica story on this first image includes a link to the full image I haven't noticed in any of the other references mentioned (or I may simply have missed it):
https://stsci-opo.org/STScI-01G7JJADTH90FR98AKKJFKSS0B.png

Filip Larsen · Jul 12, 2022

phinds said:

what's the big deal w/ 4.6 billion years old?

I understand this to be the distance to the SMACS 0723 group, not the faint galaxies in the background.

pinball1970 · Jul 12, 2022

Im furious. What is the point of setting a date have this dramatic count down after 198 days of biting our nails then release an image. The night before?

It's kind of tainted it for me. The purity. It's like uncle Barney turning up drunk on Xmas Eve morning and opening one of your kids Xmas presents and handing it to them over toast and marmalade.My day is still as planned. Day off work with the OFFICIAL time of first light.

pinball1970 · Jul 12, 2022

berkeman said:

Yeah, what the heck does Biden have to do with a NASA release? And the news articles say it would happen at 5:30PM US Eastern Time, which was an hour ago and no images anywhere that I can find so far...

Yes not happy. I've barely looked at the image. First light for me is 3.30pm BST.
EDIT. Today!

pinball1970 · Jul 12, 2022

[quote of now-banned member deleted by the Mentors]

Nothing to do with that. I am British and actually thought this administration would be more pro Science. That's good.
My point is there was a schedule, a critical path that people have been following for months admiring a MULTI national Scientific collaboration.
ESA, CSA and NASA plus private companies.

If senior members of government or the CIC wanted a private viewing before anyone else that's fine.
Ticker tape parade and huge party afterwards that's fine. I'm sure NASA have already and have plenty more champagne on ice.
11th hour televised viewing for me is hi jacking the event to feed off the publicity.
Probably not his idea.
Anyway this post could get bumped. That's fair enough, the P word is not discussed on this forum.

The ACTUAL event is in a few hours, 199 days of waiting. Day 198 I will forget for now. Time to check Webb to see if the final mode is complete.

Jarvis323 · Jul 12, 2022

This structure stands out as the strangest in the image to me. Any idea what it is?

JLowe · Jul 12, 2022

Whether you like Biden or not its just seems a bit silly to have any president present this.

In any case, i thought it clearly said on NASA website that the galaxy cluster imaged at 4.6 billion years old was gravitationally lensing some background galaxies, of which are far older and sharper than the Hubble images, on less exposure time.

phinds · Jul 12, 2022

JLowe said:

Whether you like Biden or not its just seems a bit silly to have any president present this.

It's normal for US presidents to make photo ops out of anything good that happens on their watch. Nothing new or odd about that and certainly not silly, given American politics.

fresh_42 · Jul 12, 2022

phinds said:

It's normal for US presidents to make photo ops out of anything good that happens on their watch. Nothing new or odd about that and certainly not silly, given American politics.

Advisor to Nixon: "Keep it short. It isn't your merit."