Here’s a meridian transit observation of the region around Sgr A–the
source near the center of our galaxy.
http://www.propulsionpolymers.com/radioastronomy/galactic_plane.png
There’s lumpiness due both to receiving system instability, and the fact
that the galactic background radiation is not
uniformly distributed in intensity. Around 16:20 or so, there’s some
interference from the Sun, since it
transited only 2 beam-widths above where I was pointing. I annotated
it with TGIF.
The quasi-discrete source at the galactic center is driven by a
postulated black hole. The physics are complicated, but
part of the emission is thermal, due to heating of the surrounding gas
and dust by gamma and x-rays coming out of
the event horizon around the black hole as matter falls into it.