On Sep 3, 9:14 pm, Radium wrote:
On Sep 3, 1:08 am, Martin Brown
wrote:

On Sep 1, 5:16 am, Radium wrote:
On Aug 30, 4:33 am, gwatts wrote:
Radium wrote:
What is thehighestradiofrequency used forradioastronomy?

I suppose it depends what exactly you mean by "radioastronomy".Radio
astronomers have been extending the originalradiotechique of Earth
Rotation Aperture Sythesis up into the IR and near optical bands
recently. As such thehighestfrequency at which a fringe baseline
correlator has been operated forastronomyis now in the visible band.
COAST and the NRAO optical interferometer group have both produced
indirect images of the sky usingradiocorrelator methods implemented
by very cunning mechanical optical bench designs at visible
wavelengths.

Aradio-wave can travel a larger distance with less attenuation than
an infrared or light wave. Objects in the path that allowradio-waves
to pass undisturbed can have a serious impact on optical
telecommunications.

Make your mind up. You asked about the highest frequency used by radio
astronomers.

If you read on a little farther you'll find
'blurring the distinction betweenradioastronomyand infraredastronomy.'
Many of the early microwave groups spun out ofradioastronomy
sections. The catch is that at least for a while the non-thermal
sources get significantly fainter with increasing frequency (fewer
higher energy photons get emitted).

Microwaves have characteristics that more closely resemblesradio-
waves than light/infrared waves.

They are all electromagnetic radiation. The transparency or otherwise
varies somewhat with wavelength.

So where do you want to draw the line betweenradioastronomyand
infraredastronomy? There's you're answer.
Sorry, I meant to ask whether 3,438 GHz is thehighestradiofrequency
used to receive audio signals from outer space. I should have made my
question more specific.Radio-astronomers study sounds from the sun as
well as visual data.
Although they do study movements of the suns surface by Doppler shift
of known reference spectral wavelengths this is something entirely
different to whatradioastronomers do. Very few bigradiotelescopes
enjoy being pointed at the sun.

What happens to aradiotelescope when directed toward the sun?

The receiving electronics get warmed up by the partially focussed
image of the sun. Or in the case of a catadiotric design the secondary
reflector gets warmed up and potentially distorted by thermal
expansion.

Scopes intended to be pointed at the sun are designed with that
purpose in mind.

There is no carrier wave (unless you happen to chose a specific
naturally occurring spectral wavelength like 21cm neutral hydrogen for
instance). The telescope operator choses the frequency and bandwidth
they receive - the source is normally a broadband emitter.

I would guess the higher the frequency of theradio-wave reception,
the better it is for this application. This is because higher-

Not really radio astronomy is now operating between around 35MHz and
upwards. There are difficulties with gettign coherent signals, but
once 3 or more scopes are linked together there are good observables.

The biggest problem for radio astronomy is that radio objects mostly
get dimmer with increasing frequency. And there are some bands like
the terahertz where there are very few natural processes capable of
emitting them.

Most objects emit broadband thermal radiation determined by their
characteristic temperature and broadband non-thermal radiation
determined by a combination of shockwaves, magnetic fields and fast
particle interactions. It would sound like the white noise on a
detunedradioreciever if you were to put it on a speaker. Pulsars are
the only obvious exception where there is clear periodic structure in
the signal.

What would the pulsars sound like in this experiment? Square-waves?

No. They are sharp narrow pulses roughly 1:100 to 1:1000 mark space
ratio with a broad spectrum of harmonics (a square wave would be 1:1).
You can listen to some pulsar waveforms online at Jodrell Bank:

http://www.jb.man.ac.uk/~pulsar/Educ...ds/sounds.html

Regards,
Martin Brown