Hi Andrew,

There are two ways to clean this up.

You can edit 'comets.dat', delete the asteroids, then
adjust the number at the top of the file to reflect the reduced
number of objects.

The method described by Alan Cahill will also work, except
that you'd lose your comets as well.

Or you can replace 'comets.dat' with this file:

http://www.projectpluto.com/comets.dat (about 50 KBytes)

which will cause you to have a current set of comets, with
no asteroids mixed in. That's the path I'd recommend.

(In the current version of Guide, those links to get TNOs,
critical list objects, etc. are strongly deprecated. I am
tempted just to get rid of them completely.)

-- Bill