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Old January 2nd 19, 08:09 AM posted to sci.astro.research
Steve Willner
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Default Cosmological Problems

In article ,
(Phillip Helbig (undress to reply)) writes:
Visible light is about 0.4 to 0.7 microns (400 to 700 nm (nanometers),


That range is what the human eye can see. In practice, the term
"visible" often refers to light detectable by instrumentation
suitable for visible light, say from 300 nm (the atmospheric cutoff)
to 1000 nm (the intrinsic silicon limit).

there is a bit of overlap between HST and JWST.


JWST's short-wavelength limit is 600 nm. Its prime range is roughly
1000 to 3000 nm, and the long limit is 28000 nm (=28 microns).

JWST is more or less a normal reflecting telescope, with a CCD as
detector.


Detectors are actually infrared hybrid arrays, not CCDs. They are
based on the "HAWAII-2RG" technology:
http://www.teledyne-si.com/products-...d-fpa-products

You can easily search for "Planck focal plane" on the web and find an
image showing lots of horns and other radio-astronomy stuff. Planck has


I think "had" for that last word above.

a wide frequency range, with frequencies from 30 GHz to 857 GHz,
corresponding to wavelengths between a centimetre and about a third of a
millimetre, the latter being about 300 microns. Typical traditional
ground-based radio astronomy is in the GHz range and below, so
wavelengths from centimetres to metres.


Frequencies up to 15 GHz (wavelength 2 cm) were pretty common even
when I was in school. Nowadays, the VLA
https://public.nrao.edu/telescopes/vla/
makes images up to 50 GHz, and ALMA
https://public.nrao.edu/telescopes/alma/
goes up to 950 GHz (though I don't think the highest frequencies are
100% operational yet).

https://space.mit.edu/home/tegmark/movies.html
In the plots, as usual, larger angular scales are on the left, smaller
ones on the right.


Yes, very nice.

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