OK it is really late here, but today's reveal of the first JWST image of the galaxy cluster SMACS-0723 was amazing, and I am still digesting it. There is so much stuff going on, it is absolutely breathtaking!

Just to get an idea of what an improvement this is over Hubble, over at The Robot Report, they show this beautiful side-by-side view of the previous best image taken with Hubble, and tonight's result. It's wild.


So, I guess the left is a Hubble visible spectrum image, whereas the JWST image is infrared, mapped to RGB color bands for display.

Reading about this, it looks like NIR only images 2-bands, roughly centered at 2μm & 4μm, not three, so they've remapped the colors in some way to generate the 3-band color image we see.

Not sure exactly how they do that, but I'd naively assume something like red = B, green=(A+B)/2, blue=A, where A is the 2μm band and B is the 4μm.

@TerryHancock My guess is that the HST imaging is mainly in infrared - Hubble's sharpness in UV and Optical is comparable to JWSTs in the near-infrared. But Hubble's sharpness is quite dramatically worse in the IR, as is also clearly visible here.

@TerryHancock ...And according to STScI, the JWST image is actually taken in all six broad NIRCam filters, with each color representing a stack of two filters as seen in this image:


These details should be in the press release. This is the entirety of what the damned thing says about wavelength:

"This deep field, taken by Webb’s Near-Infrared Camera (NIRCam), is a composite made from images at different wavelengths, totaling 12.5 hours – achieving depths at infrared wavelengths beyond the Hubble Space Telescope’s deepest fields, which took weeks."

I'm not mad. I'm just _disappointed_. 🤨


@TerryHancock I agree, but we should remember that today's preview briefing for the US president was just that, a preview briefing, seemingly planned quite hastily, so all that information might come out with the planned image release tomorrow.

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