[amsat-bb] Re: Long time eclipse prediction

Roger Kolakowski rogerkola at aol.com
Tue Jan 29 06:01:16 PST 2008

Hi Chris...

My simple understanding...

If you display the Sun's location and daylight/nighttime line on your
display along with the ground coverage of the satellite, the intersection of
the daytime line and the satellite's circle of visibility will indicate when
the sat is in sunlight.

As most satellites "progress" daily in longitude in relation to standard
time you will be able to visualize their approach toward eclipse or

By increasing your time increment in the program (fast forwarding) you can
guesstimate when these transitions will occur in the future.

I say most satellites because some satellites such as the NOAA's are
launched to be almost "sun synchronous" and will pass overhead almost at the
same time every day.

For the more technical explanation I must bow to the real orbital engineers.


----- Original Message ----- 
From: "Chris Bloy" <chris at photofuture.co.uk>
To: <amsat-bb at amsat.org>
Sent: Tuesday, January 29, 2008 8:15 AM
Subject: [amsat-bb] Long time eclipse prediction

> Hi All,
> I have never been able to get a straight answer on this one, but does
> InstantTrack or any other program show you the long term
> non-eclispse/eclispe period, or is there a way to calculate this?
> How do we know that PCSAT and UO11 are going to HIT sunlight or not for a
> period of time?
> I can see from Orbitron the realtime, but not anything in the future?
> Thanks,
> Chris
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