Tue, 13 Dec 94 11:03:15


Some replies from Bjorn Gimle, Sweden. Like Dave, I will gladly help you
get started, and answer further question on these subjects :

>From: Ryan Rudnicki <>
>Organization: Southwest Texas State University
> I forward the following message for two reasons.  First, to the beginner
> satellite watchers the following information may be of interest.
> Second, I wonder if the seasoned satellite observers use the star map
> technology Dave refers to toward the end of his post?

I rely on Rob Matson's SkyMap for both planning and reducing the results 
from my observations. I have followed the evolution of the program, and 
influenced it for several years.
> Until now, folks take the predicted positions of satellites generated
> by a program like Mike McCants' Quicksat and transfer RA & declination
> to a star chart for use in the field when observing the actual satellite. As
> far
> as I know, folks have been using traditional star atlases. Is there anyone
> out there who has used a digital star atlas/program and printed out an
> evening's worth of maps on their laser printer? Afterwards the maps can
> be annotated and filed or discarded (recycled).

I use SkyMap for this, but I seldom print out the maps - partly because I
don't have a laser printer at home, and the picture quality on an old 9-pin
Epson printer is inferior to the screen. SkyMap saves all the parameters
you set, including a map title, in a configuration file, which you can name
to keep multiple displays available, and if you have a math coprocessor
it is faster to regenerate a plot, than to print it. And you can use
cursor keys to recenter and rescale the plot, and change projection.
And, which I find very important : after the observation, you can use
the cursor crosshair to find magnitudes and positions of your reference 
stars, and directly read out the position of your observations.

The plots can also be svaed on different files, in the HP-GL text format,
which also can be used for annotations and other postprocessing. There are
separate utilities that can plot these on hundreds of different printers,
or on PCX files, or VGA/EGA screen, with rescaling , and panning, so you 
can find details of plots, even if you do not have a coprocessor, and think
re-plotting takes to long.
> If so, which star map program is best or the most widely used? Has an
> interface been written between the satellite prediction program (Quicksat,
> Traksat, ...) and the star chart program so the process from prediction to
> map production is automated? If so, between which prediction/star atlas
> programs? 

The configuration files of SkyMap are (almost) MicroSoft standard type, with 
keyword=value, so they are easy to edit outside of SkyMap, or to create them 
by a preprocessor/interface program as you suggest. There is also a PC Mag
utility that can be used to change single values in the file. Standard
Windows routines also exist to Get/Put values from these (.ini) type files,
so a Windows interface could also be done easily. I have been considering
writing one between QuickSat and SkyMap - partly because I remember my 
frustation when running without a coprocessor, and running plots of the 
wrong area or time, partly because I still use Quicksat and its magnitude
and flag characters in the reference file as a means to get a desired subset
to consider for observation. SkyMap also has a magnitude screening capability,
in addition to elevation/perigee/range/time limits, and can produce a list
of all passes, with three positions per pass, but does not display all the
name, magnitude and other comments that QuickSat does.

> Has anyone used the SkyMap program mention by DM below?  The
> only SkyMap I know of was written by a fellow in England and can be downloaded
> from a machine in the UK. The SkyMap program to which DM refers was apparently
> written by a fellow in San Diego, California and I'm not familiar with it at
> all.
> Ryan Rudnicki
>Another program is even better for finding visual passes if you can
>figure out its arcane menu structure.  This is SkyMap and it plots
>"near publication quality" star maps and then plots the satellite's
>path across them.  Once you figure out how to tell it to do so, that
>is.  SkyMap also has a great search routine that finds future visible
>passes very quickly - again, if you can figure out how to do it.

I do not agree with Dave's criticism of SkyMap's menu system - I tried
using TrakSat 2.80 (although 3.xx is said to be friendlier) and was
irritated by the fact that the choices you make can not be saved for
future runs, and many menus force you to reenter a series of choices,
even if you just need to change one, or just call it up to explore it !
Also, I find the map flexibility and precision inferior to SkyMap's.
>Both programs are widely available on BBSes and can be found on the
>Clear Skies BBS in Madison, WI at (608) 249-7130.  I've also just
>uploaded them to  Look for these file names:
>TrakSat: TRAK280A.ZIP, TRAK280B.ZIP
>If anybody has any questions, I'd be happy to help.  Email me at

And,   and probably also