This was put up by NASA a couple of days ago, so why didn’t we hear about it? But It shows that WE DID IT, and by “we”, I mean “humanity”. Getting that big and complicated puppy into space was a fantastic achievement and now it seems to be working. First, the image:
It’s the same star pictured 18 times—once in each mirror. Yeah, so doesn’t seem so exciting, does it? But it really is, because it shows the telescope works and the mirrors can now be tweaked to take the pictures the Webb was designed to take. (The different images of the same star will be brought together.) As NASA explains:
The James Webb Space Telescope is nearing completion of the first phase of the months-long process of aligning the observatory’s primary mirror using the Near Infrared Camera (NIRCam) instrument.
The team’s challenge was twofold: confirm that NIRCam was ready to collect light from celestial objects, and then identify starlight from the same star in each of the 18 primary mirror segments. The result is an image mosaic of 18 randomly organized dots of starlight, the product of Webb’s unaligned mirror segments all reflecting light from the same star back at Webb’s secondary mirror and into NIRCam’s detectors.
What looks like a simple image of blurry starlight now becomes the foundation to align and focus the telescope in order for Webb to deliver unprecedented views of the universe this summer. Over the next month or so, the team will gradually adjust the mirror segments until the 18 images become a single star.
“The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding. We were so happy to see that light makes its way into NIRCam,” said Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy, University of Arizona.
Click the screenshots below here for more:
Here’s a 3-minute video showing first image arriving at NASA. We haz photons! But watch the second video as well.
If you want a hyper-enthusiastic summary of what this photo is and means, here’s Dr Becky Smethurst from Oxford. Her bio at the YouTube site:
I’m Dr. Becky Smethurst, an astrophysicist at the University of Oxford. I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don’t know. If you’ve ever wondered about something in space and couldn’t find an answer online – you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.
If you want to understand what Smethurst means by “naff,” reader Don, who sent me this link, also points to a page explaining that British term.
Re James Webb: Most of the individual images of the moderately bright star (HD4406) can be seen to be fairly poorly focused. Before using the six actuators on each mirror to overlap the images, a seventh actuator at the center of each segment is used to adjust the mirror curvature and improve its focus.
So the curvature of each of the 18 segments can be adjusted? Will this be done constantly, every time a new object is imaged, or does the initial focusing last a long time?
Ignore me and just check Docbill’s video at #6.
I somehow missed that, thanks!
Besides defocus, some of the images are elongated and show astigmatism or something. Can the actuators be used to adjust the curvature so as to correct such aberrations?
Video 1 – Great animations to explain what’s observed and the process. The James Webb telescope selfie is amazing!
Video 2 – Fine but too hyped for my taste like a Youtube influencer trying to get likes after dropping a reaction video to the latest Adele song.
Smethurst ordinarily “love making videos about science with an unnatural level of enthusiasm” with a blooper reel ending, and had worked a full day including such videos, so I’ll give her some leeway.
Besides all other factors she works on active galaxy black hole feedback, and has mentioned that the James Webb will set the early universe baseline for her. Happy scientist is happy.
Agree. No disrespect to Smethurst who is an actual astronomer and I’m not denigrating her enthusiasm. We need both excellent scientists and excellent science communicators and popularizers to engage the public, especially when significant tax money goes toward these technological marvels.
That is way cool! Pictures of stars commonly have rays on them, and those are made by light diffraction around the suspension struts that hold the secondary mirror. Since the secondary mirror of JWST has 3 such struts, I wonder if its star pictures will also have rays later on.
Blow the image up. Some of the images, largely on the left, have the 3 (or 6, depending how you count) “rays” on them. I am more concerned about the elongated images on the right, which look like they have some kind of astigmatism, tho not necessarily the aberration called astigmatism. I do not know enough to say any more.
Ball Aerospace – not just a jar company!
Check out this video about the mechanism that adjusts each of the 18 mirrors in six degrees of freedom. It’s pure genius!
https://youtu.be/5MxH1sfJLBQ
Brilliant, that is a great demonstration.
Brilliant news, I’m glad everything is going to plan.
Great progress! This means there will be science down the line.
Mind that besides that the mirrors are not aligned and curvature adjusted, the still hot instrument adds noise as per the JWST team explanation [ https://www.youtube.com/watch?v=QlwatKpla8s&ab_channel=JamesWebbSpaceTelescope%28JWST%29 ].
The news started to trickle out Friday evening here in Europe, apparently after 18 hours or so work on getting the first full data transmission load down and verify both the instrument, the target star pointing and the mirrors. So the first articles appeared just yesterday during the weekend news lull.
Here is the current status and remaining work on the mirrors – it seems to me there are 8 more steps using up 14 weeks before the instrument calibration will start [ https://webb.nasa.gov/content/webbLaunch/whereIsWebb.html?units=metric ].