Re: Tracking satellites with Meade ETX-90 EC

Ron Dantowitz (
Sun, 28 Mar 1999 01:46:55 -0500 (EST)

At 11:37 PM 3/26/99 -0500, you wrote:
>>> Dave Mullenix <> said:
>>> >Meade has a new telescope out, the ETX-90 EC.>
>>Philip Chien wrote:
>>> The key question is whether or not you can update the elements yourself.  I
>>> would be very concerned if the data was in a proprietary format which may
>>> or may not be supported in the future.
>>> The other question is what satellites are in the database.  It's quite
>>> possible rocket bodies and debris may be left out as 'uninteresting'.  More
>>> important is the satellites which may or may not exist where the elements
>>> don't come from OIG.
>>You should be able to select the satellites yourself, but the software
>>and connecting cables aren't available yet.
>Ah - good old vaporware.  I wouldn't purchase something like this unless I
>was *sure* that I'd be able to continue to use it on my own, especially if
>the company decides not to support it at some date in the future.
>>The computer does come with
>>some satellites pre-loaded in its data base, but the elements probably
>>date to last January.
>which kind of limits the usefulness of the device if there's no way to
>update the elements.
Hello fellow satellite enthusiasts!

I though I would put my $0.02 in on the following:

>>Has anyone used
>>satellite tracking software for telescopes to find and track objects?

And the response:
>Quite a few have, including those who have put together their own systems
>from scratch (or existing components not intended for satellite tracking)
>and those who have purchased commercial units.  I suspect Ron's the most
>well known primarily because of his Sky & Telescope article.
>I've been told about French observers who have imaged satellites including
>the classified U.S. NRO Keyhole birds.

I am wondering if these folks referred to are Alain Grycan and Eric Laffont?
I believe they used a C11, but I am not sure.  The problem is not so much in
tracking satellites, in fact you can track satellites by eye or even in a
scope by hand...

The EXTREMELY difficult part is tracking satellites so smoothly that you can
image them! On our CCD camera each pixel is only 0.2 arcseconds across...
that's equivalent to only 400 yards on the moon.  This is a good trick to
begin with, but it is even worse when you realize that an object traveling
at, say, 1 degree per second covers 18,000 pixels every second!  This level
of control requires more bits of resolution than most control systems have.
We use a 22-bit control system manufactured by Merlin Controls Corporation
( and a Meade 12" SCT.

I am most interested in learning more about anyone else who has been able to
image sats... it is a real challenge, but the most fun I have had in years. 

>I've been told about French observers who have imaged satellites including
>the classified U.S. NRO Keyhole birds.
Imaging is no probs... but resolution is tough.  I suggest video over
imaging any day in order to "beat the seeing".  A 12" SCT can resolve
details on the order of 12 inches in LEO- not bad... then why have
classified satellites remained hidden so long, if even amateur telescopes
are often in the 20", 30", and sometimes 40" range? Well, the more
magnification you use, the more noticeable (and degrading) even slight
vibration is. All the problems of finding these objects (daytime or night),
and getting them in the eyepiece is not easy... but to get them on a chip
and staying on a pixel is still difficult for current technology this side
of $$$,$$$.  

So, if any Government folks are lurking on this list (Hi guys) they can rest
assured that their satellites are still kind of safe from peeking except for
the Merlin hardware and perhaps the french guys and of course the zillion
$$$ government mounts.  They should not fear the Meade ETX... the
combination of resolution and tracking "smoothness" do not exist in this
device sufficient to pose a threat.  But it sure looks like great fun for
more potential seesaters!

I encourage as many people as possible to try tracking by hand or computer!
Great fun indeed.