Viewing a single comment thread. View all comments

Riegel_Haribo OP t1_itfkm45 wrote

Maybe closer to a thousand cosmic ray artifacts across six different filters, from Webb's NIRCam sensor being struck by high-energy particles during long exposures, leaving both a ring-shaped halo when they are removed, and a picture peppered with dots when they aren't recognized by the ground processing.

With other tedious astro magic; I think I improved a bit on another "I processed" post from earlier this week: https://i.imgur.com/Pxy42Mh.png (we can now recognize the mirrored image of galaxies)

This galaxy's fireworks show is sure to challenge our understanding: https://i.imgur.com/oaaNUM9.jpg

28

bk15dcx t1_itfnv2c wrote

What's causing the gravitation? I don't see a black hole or any dark matter.

1

Riegel_Haribo OP t1_itfondo wrote

Mass, warping spacetime. (Let me know when you invent a telescope that sees "black" and "dark" things...)

Abell 2744 is itself featured on the Wikipedia gravitational lens page.

14

bk15dcx t1_itfra8b wrote

So it's mass we cannot see?

And yes, I'll let you know when my breakthrough telescope is ready.

8

sight19 t1_ithl319 wrote

Dark matter of the galaxy cluster is causing lensing. It actually warps background galaxies even on relatively large angular distances from the cluster (what we call 'weak lensing'). This only produce a small effect, but if we stack this effect, we can effectively 'draw in' the shape and location of the DM in the cluster. This has been done before, in for example the Bullet cluster or the Toothbrush cluster (I know, we are really creative with names here...)

1

wowsosquare t1_itigqkw wrote

AMAZING... and I never thought about cosmic rays and the space telescopes. Now that I think about it, how do we get any of these great pictures, given that the telescopes and their sensors are constantly being blasted with these high energy particles

1

Riegel_Haribo OP t1_itj4tby wrote

They could certainly be handled better than they currently are in STScI pipeline processing. Here is just one filter of this observation: an area with full coverage of the four dithers, made of exposures with ten integration groups each... and we still get the halo rings of poorly-removed "snowballs" peppering our picture:

https://i.imgur.com/aVEQDWB.jpg

Now overlay six layers of that.

And here's an animated GIF of the exposures that make up a dithering, with the constant sparkles and some incidental streaks of lower energy cosmic rays that should have been cleaned by earlier ramp jump detection, becoming a background noise:

https://i.imgur.com/lE8Yqyl.gif

You can see some of this in a square at the center of the left edge of the Abell image with low dither coverage.

In the last frame of the GIF, see both a "removed" snowball in the middle, and an unremoved blob at the lower edge.

The solution is many more shorter dither observations, and processing that takes a comprehensive start-to-end removal strategy.

3

wowsosquare t1_itk0jkk wrote

W9ow I didn't know so much thought went into making these!

3

Alien_Fruit t1_itk5qg2 wrote

I was just about to say the same thing! It must be an exhausting job, cleaning up these images! But the result is fantissimo!

3