Hi, I've got a couple of suggestions that hopefully (!) will be
trivial to implement.
Firstly, elements.txt has a nice output of the most recent fit orbit
which includes keplerian and rectangular/cartesian coordinates. I'd like
to see this file get appended to when producing a series of
monte-carlo orbit (and please keep the heliocentric ecliptic elements
for the position/velocity coordinates!) so the net result is this
file will have 50, 100 or whatever clone data sets.
Secondly, there should be a way of getting a set of the planets'
position/velocity coordinates for whatever epoch is used for the
fitting. The main thing is that it has the exact same reference frame
as the output asteroid coordinates. I'm planning to use this for some
integrations of various trans-neptunian objects. Probably it should be
a different file from all the above outputs, and it shouldn't be
recalculated at each step of monte-carlo generation!

Cheers, and thanks for a great program!

Andrew

PS The comment above about heliocentric coordinates is because both
the Mercury and Swifter integration packages use them for
initial conditions.