[amsat-bb] Re: Hitting a southbound Moon

i8cvs domenico.i8cvs at tin.it
Wed May 12 22:47:37 PDT 2010

----- Original Message -----
From: "Greg D." <ko6th_greg at hotmail.com>
To: <amsat-bb at amsat.org>
Sent: Sunday, April 25, 2010 8:34 PM
Subject: [amsat-bb] Hitting a southbound Moon
> Hi folks,
> Now that the Arecibo event is behind us, there is still one puzzle that
> I'd like someone to explain to me.  How do I aim at the Moon?
> I'm on the US West Coast.  Early in the pass on Saturday, both Predict and
> Orbitron told me that the Moon's azimuth from here should be slightly
> north of east.  It was in the 80-ish degree range, with east, of course,
> being 90.
> But looking at Orbitron's map display, the Moon was clearly south of my
> latitude.  As the pass progressed, the >Moon moved westward on the map,
> making a sharper angle to the south of east from here.  Both Predict and
> Orbitron's Az calculation increased too (eventually crossing 90 degrees),
> but always seemed to be north of where >the Moon was.
> Why would I aim north to hit a southbound Moon?
> Greg  KO6TH

Hi Greg, KO6TH

It was only the Sub Satellite Point SSP of the Moon south of your latitude
on the earth surface i.e. the map display but the Moon as seen from your
locator was north of your latitude over the celestial sphere up in the sky
and this is why you aim north the antennas to hit the Moon even if her SSP
on the map has a southbound path.

73" de

i8CVS Domenico

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