RE: [amsat-bb] Navigation help for AO51 wkg Pacific Maritime Mobile

["A.J. Farmer" <ajfarmer@xxxxxxxxxx>]

I'm not sure if Satscape will do it, but Nova will do pass predictions for
when a satellite is within view of two locations at the same time.  You
could easily use this feature to get a range of times to try to make a
contact.

73!

A.J. Farmer, AJ3U
http://www.aj3u.com


-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org] On Behalf
Of graham@southline.demon.co.uk
Sent: Monday, September 27, 2004 4:56 PM
To: amsat-bb@AMSAT.Org
Subject: [amsat-bb] Navigation help for AO51 wkg Pacific Maritime Mobile

Hi Amsat folk.

I need some help to figure out a schedule for G4FVG who is at sea on the
Pacific Ocean. When AO51 "Echo" presents a path  between the ship P & O
Nedlloyd "Mercator" and any land mass that might contain a few of us guys
trying to work AO51, he would like to work the satellite - or at least hear
it! His call might be G4FVG/MM.

I have the suitable software (Satscape) to provide a list of pass
predictions
for known times in the future. The problem is that this is a big powerful
ship
that moves to a new lattitude and longitude between AO51 passes. This is
about what to do if the QTH is also moving!

I would much appreciate some pointers as to how to figure out great circle
routes between known locations, so I can get a set of UTC times that
correspond to his earth positions. I need a the formula, and maybe some
usage procedure. Then I think it has to be done by creating a whole load of
these (temporary) QTH positions in Satscape, and making it generate a few
passpredictions for each.

I know he was at 41-40N  143-00E (Japan) at  19:09 GMT on 26th Sept 2004.
He is heading for 48-28N  125-20W (Vancouver) eta 15:24 GMT on 3rd October.
The route is a southerly dip great circle with a midway point 41-40N
175-00W , which would be reached at 00:16 on 30th September. I understand
they try to keep the ship speed constant.

Hmm.. maybe time to dig out those old college math notes!

Thanks for any help.
Graham G4WNT
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