JWST has 4 different instruments on it. While they all share the same focusing mirrors, but otherwise are 4 different measurement devices.

For the red dot observations, I believe this things have been measured by at least 3 of the 4 devices on board - NIRCam (near infrared camera, has very limited spectral capabilities through its filter wheel), NIRSpec (near infrared spectrograph) and MIRI (mid infrared instrument).

I cannot pretend to have the actual expertise, but it does seem vanishingly unlikely that all 3 instruments could create consistent artefacts in the same location.

If you're worried about bad pixels or noise, it seems like there is an easy fix: point it in a direction specified by some angles theta & phi, wait long enough to accumulate light from distant faint objects (high redshift galaxies etc), then shift Webb's orientation by a small amount to theta+delta_1 & phi+delta_2, which will have a significant overlap with the original image, and after taking the 2nd image check to make sure that all the objects have shifted over together by the same amount...

Some of the Hubble results were also raising questions. At the same time, I read one of the papers on the galaxy stuff, and what struck me was they were identifying galaxy shapes by counting the pixels each galaxy had, so there are definitely some question marks over how they do some of this.

> what makes us so certain that we can trust what we see on James Webb?

We can trust what we see. We can't trust there's nothing where we don't see anything.

astro1234, your account is dead for some reason - you might consider emailing the admins.

I vouched for your two posts in this thread, but that never works, and honestly it gets a little old trying to pick up the slack left by HN's inscrutable, unaccountable, and largely-broken filter. This has been happening a lot lately, unfortunately.

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This is one reason to dislike the NASA process of building one huge prestige telescope every few decades.