RE: Orbit's pole

Richard Baldridge (
Fri, 24 Jul 1998 10:48:00 -0700

You can never have an exact match for a track using what you suggest,
(except for a pass that goes through the zenith), but you CAN greatly
improve the ease of tracking following your train of thought.  The
reason it cannot match exactly is that satellites follow linear paths
across the earth's surface and do not "orbit" or follow great-circle
paths around the observer (except when the orbital plane passes through
the observer, i.e. satellite passes through zenith).

I have used the method you describe with good success. A simple formula
for pointing the polar axis of your scope is to take the ALTITUDE and
AZIMUTH of the satellite's culmination point and use them in the
following calculations.  The altitude that your polar axis should point
at would be:    90 - (max. satellite altitude).  The Azimuth that your
polar axis should be pointed at would be:   Satellite Azimuth at
Culmination - 180.  Of course you must put this azimuth in a 0 - 360
degree range by adding 360 to the answer if it is less than 0.

What will then happen is at culmination the "declination" your telescope
will be set at is "0", but before and after culnimation it will be less
than "0" to follow the satellite, except (again) it will track very well
when a satellite passes through the observer's zenith.  But then, you
don't need to tilt the axis at all.  I've seen detail in the Shuttle
(wings, cockpit section and vertical tail) and MIR with a 12" f7
Dobsonian at 150X moved by hand by simply waiting until a pass was
directly overhead!  This obviously limits the opportunities, but
patience pays off!

This is crude, and I'm sure there are others out there who have a better
method of approximating an observer's satellite orbit "pole" that would
make tracking with a properly tilted 2-axis scope even easier.  I'd also
be interested in hearing of other (and better!) methods.

Rick Baldridge, Campbell, CA   N37.262   W121.977   72M

From: Grzegorz Koralewski
To: SeeSat Mailing List
Subject: Orbit's pole
Date: Friday, July 24, 1998 9:31AM

Hi SeeSatters,
I've tried to see the structure of Mir several times,
but tracking it with my equatorially-mounted Newtonian
has always been a barrier.
Recently I thought, that actually hand-tracking would be
much easier if I knew where the pole of the orbit
was. What I'm looking for, is a computer program that
will tell me RA and Dec of the orbit's pole. I would have to
care only for one axis then.

                                        Clear Skies,
                                        Grzegorz Koralewski
                                        53.37N 14.65E 100M