On 11/27/18, Ken Thompson via TUHS <tuhs(a)minnie.tuhs.org> wrote:
another joe:
echo 1 was a 100 foot balloon that was
launched into space in the early 60s. this
was the first satellite that was easily visible
to the naked eye.
joe wrote a set of fortran programs that
tracked the orbit of echo and calculated
the direction to look from a point on earth.
to do this, he had to learn fortran and
orbital dynamics.
by the time i came to bell labs (1966) the
program, azel, for azimuth/elevation, was
expanded to track planets, moons, satellites,
etc. moreover, it tracked the shadow of the
earth cast by the sun (night). it could predict
within a few seconds when echo would wink
on or off as it passed through the shadow.
a version of azel was maintained all the time
i was at bell labs. we used it to predict
eclipses, transits, occultations etc. when
we first got a voice synthesizer, the day's
predictions were spoken at 5pm in case
there was anything interesting.
What a great story. There is today a website (
heavens-above.com) that
does the same thing as Joe's azel. Amateur Astronomers visit it
regularly to get the night's predictions for visible satellite
transits, visible passes of the International Space Station, etc. I
had no idea the idea went back that far.
-Paul W.