S03:E04
The one that should have been caught earlier.
An instrument does not see a rectangle. It sees a tilted patch inside one, and reflecting the frame about its diagonal moves that patch — so every pixel the telescope covered on one side of the mirror and not the other is subtracted against nothing and comes back at full strength. Across sixty-four cubes, that edge is most of what this technique was reporting. On the worst of them it is 99.6% of it.
The first movement is one such cube with the edge left in. The second is the same cube, at the same scale and the same gain, with those pixels removed. It runs three minutes and twenty seconds and it is silent from end to end. That is the finding, not a fault: nothing that cube was telling us survived the removal of the telescope’s own shape. The third movement is that silent piece again on its own scale, so you can hear that something is there — about forty decibels below what the first movement was calling the sky.
Then an Einstein ring, twice, the same way.
Source: JWST MIRI and NIRSpec IFU, programs 2926 and 5883.
A note on the silences: this piece runs quiet for 6m58s in total, the longest stretch 3m24s. Nothing is wrong with the file.
The silence is the recording. Each piece here is a subtraction: two files put on one scale and taken away from each other, with agreement rendered as silence. Where you hear nothing, the two files agreed.
