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Discussion in 'Environmental Discussion' started by bwilson4web, Jun 17, 2021.
Here is a description of current capabilities of radio astronomy:
Technology | Event Horizon Telescope
Towards the end it considers imaging the black hole central to our galaxy. Goal is 10 micro arc seconds.
Optical astronomy is 3 orders of magnitude coarser than that and that gap may persist. I wish we had a real astronomer here to teach about what work at what wavelengths might reveal what.
If any aspect of earth human technology draws attention from other galactic civilizations (if they do exist), it will be this. Not cars and not medicine. Sorry, guys.
On a tangentially related note ...
Physicist (and astronomer) Steven Weinberg passed away Friday, at age 88:
With Steven Weinberg’s death, physics loses a titan | Science News
Steven Weinberg - Wikipedia
JWST is now intended to launch Dec 18. Very long delayed and up budgeted. It will bring Hubble-scale resolution to infrared, and is larger to collect more photons. Photons are not so abundant in infrared, especially from exo planets, that optimists hope to see with it. Along with galaxies very far away a long time ago. Cue theme music.
It is intended to survive rigors of launch, unfold, and take its station more than a million km from earth. Perhaps during its service life it will become possible to go there and resupply fuel required for 'station keeping'.
Our earlier discussion here about angular resolution (could be in milli arc seconds) sent me back to possibly accurate math. Looking out from earth (or JWST's Lagrange point), the whole sky (observable universe) can be seen as a beach ball with observer in the center. If a 'pixel' spans 40 milli arc seconds, there are about 2 X 10^15 pixels to observe. That is a very large number, and target priorities will be for astronomers to contest after it comes alive. Does one JWST image cover 2 million pixels? Probably something like that, which still leaves a billion decisions about where to look. It promises to be quite an adventure.
Finally it will only be from good luck during its energetic departure, and different luck later, for JWST to approach Hubble's 3-decade run.
A plucky not-yet-interstellar civilization did this, even with only fire to push it out! Other interstellar civilizations might notice in a benevolent way. Or have they already? Bwa ha ha.
It looks like 10 simultaneous 4.1 Mpix sensors, for a total of 41 Mpix: https://www.stsci.edu/jwst/instrumentation/imaging-modes
"MIRI provides broad-band imaging at the longest wavelengths in nine filters from 5.6 to 25.5 μm. MIRI imaging has a field of view of 74”x113”, with a pixel scale of 0.11".
NIRCam imaging has two parallel modules, each with a field of view of 2.2’x2.2’, and separated by a ~44” gap. Within each module, the light is split by a dichroic and sent to a short-wavelength (SW, 0.6-2.3 μm) and a long-wavelength (LW, 2.4-5 μm) channel. Each SW module is split into 4 separate detectors. In total, NIRCam images simultaneously with ten 2040x2040 detectors, for a total of more than 41 million pixels. The short-wavelength channel has a pixel scale of ~0.031", which Nyquist-samples a point source at 2 μm. The long-wavelength channel has a pixel scale of ~0.063". Each channel has a comprehensive selection of wide-, medium-, and narrow-band filters.
NIRISS is capable of imaging from 0.8 to 5 μm with a field of view of 2.2’x2.2’. It uses a spare filter set from NIRCam and has a pixel scale of 0.065" per pixel, which matches the sampling of the NIRCam long-wavelength channel. In general, NIRCam is the camera of choice for near-infrared imaging with JWST, since it has twice the field of view of NIRISS and obtains SW and LW images simultaneously. However, used in parallel with NIRCam, NIRISS imaging can increase the field-of-view and efficiency of near-infrared imaging."
This page shows the relative positions of these and other sensors on the focal plane:
JWST Imaging - JWST User Documentation
More pregame show for JWST
James Webb's 30 Days of Terror - Universe Today
I’m more worried about the first 30 minutes….but yeah.
I take their point.
Pleasantly surprised that they haven’t had to change JWST’s initials…….yet.