[Discuss-gnuradio] Progress with the gr-radio-astronomy code

[Marcus Leech]

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.

http://www.propulsionpolymers.com/radioastronomy/cyga_sdat20060919.png

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.

http://www.propulsionpolymers.com/radioastronomy/cyga_tpdat20060917.png

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

http://www.propulsionpolymers.com/radioastronomy/dec-29_tpdat20060919.png

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.