Progress with the gr-radio-astronomy code

Here’s a plot of the redshift of atomic hydrogen in the direction of
Cygnus A. This is galactic hydrogen in the
line-of-sight, rather than a hydrogen signature from Cynus A itself,
which is bleedin’ far away (1.0e9 LY), and
it’s largely visible (to my instrument) in broadband blackbody
radiation, rather than in narrow spectral lines.
Much weaker (and more dramatically red-shifted) atomic hydrogen
signatures can be found in most parts of the
sky–the stuff is everywhere in the cosmos.

Here’s a plot of the continuum (blackbody, mostly) data for the Cygnus A
region. The little bump on the side at
around 20:00 is Cygnus A itself, while the rest is blackbody radiation
from the galactic plane–my beamwidth
is too broad (3.8degree roughly) to fully resolve Cygnus A amidst the
cacophony of the slice of our own
galaxy that sits between us and Cygnus A.

Another interesting spot is the region near the center of our galaxy, an
object called Sagittarius A:

The above is a larger-context plot, showing a full 24 hours of RA, with
Sagittarius A being the big thin
spike in the middle. This is an average of two days worth of data.
I’m hoping to get smoother
baselines, as I add more days of data. Most of the lumpiness is due
to instabilities in the receiver
of one kind or another–temperature shifts, interference, etc. Rains
and clouds will also cause
slight shifts in the baseline. Sagittarius A is a thermal-emission
region around the postulated black-hole
at the center of our galaxy. Matter in-fall across the event horizon
causes gamma radiation release, which
heats the surrounding gas and debris to very high temperatures. It’s
this incandescent debris cloud which
can be “seen” through its blackbody microwave emissions. The region
is optically dark, because of the
intervening gas and dust, but microwave observations can “see through”
this stuff.

I know that most of you aren’t radio astronomers, but I thought it would
be interesting for the assemblage
to see what is being done with Gnu Radio now. Apart from my modest
observatory here, there are two
others using the gr-radio-astronomy software, including a
somewhat-less-modest astronomical research
institute in North Carolina.

WAAAAYYYY too cool.

Bob

Marcus L. wrote:


AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
“You see, wire telegraph is a kind of a very, very long cat.
You pull his tail in New York and his head is meowing in Los
Angeles. Do you understand this? And radio operates exactly
the same way: you send signals here, they receive them there.
The only difference is that there is no cat.” - Einstein

On Tuesday 19 September 2006 21:45, Marcus L. wrote:

I know that most of you aren’t radio astronomers, but I thought it would
be interesting for the assemblage
to see what is being done with Gnu Radio now. Apart from my modest
observatory here, there are two
others using the gr-radio-astronomy software, including a
somewhat-less-modest astronomical research
institute in North Carolina.

That would be us at PARI. I’m hoping to demo the pulsar code Friday
night.
We’ve bought several USRP’s; I have two myself. Our receive dishes are
85
feet in diameter, but rather old. This means we have a job just keeping
them
running, and keeping up with lightning hits and such. But things are
a’happenin’ albeit somewhat slowly.

Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC 28772
(828)862-5554
www.pari.edu

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