Hi Lawrence,

Just thought I'd mention that to get MPC observations to show up
on-screen, you need to copy the file 'mpc_obs.tdf' from the TEXT
directory of the Guide CD-ROM, over to your hard drive.

By default, this is set up to show MPC observations from the
file 'mpc_obs.txt', but you can edit it with Notepad or your
text editor of choice and change that file name. You can then
fire up Guide, go to "Extras... Toggle User-Added Datasets",
and turn "MPC observations" on. Your observations will then be
plotted on the chart.

One nice feature of this is that you can right-click on an
observation symbol, ask for "more info", and see the time/date
at which the observation was made. Click on this, and Guide
will switch to that time/date and observatory position. If the
comet or asteroid happens to be one of which Guide is aware,
that object will then be plotted next to the observation symbol.

It occurs to me that you may be thinking not of this feature,
but of the Find_Orb software. This is open-source freeware,
independent of Guide (except in the sense that I used many
parts of Guide's code in writing it):

http://www.projectpluto.com/find_orb.htm

This software can read a file of MPC observations and crunch
through it to generate orbits. This can be entertaining and/or
educational (it's impressive to be able to go all the way from
photons falling on your CCD, to measuring positions from the
resulting images, to computing an orbit based on those
observations). It can also be useful; you can feed it your
astrometry, compute an orbit, and sometimes diagnose errors
from the residual errors.

More esoteric uses involve computing orbits for artificial
Earth satellites or natural satellites of other planets, and
(most recently) computing "uncertainty regions": that is, "We
made the following observations last year, or ten years ago;
in what regions of the sky should we look for it now?" Not
something most people will do... but if you need it, it's
very nice to have it.

-- Bill