Hi Bernd,

Regarding the "mag 99" for the comet C/1994T1 (Machholz), also
known as 1994r: the problem here is that there are no magnitude
parameters given for this object. This is quite unusual, and I don't
know why it would be; I just checked the raw data for this object
(observations from MPC), and it looks as if there were enough magnitude
estimates to allow magnitude parameters to be computed.

For a variety of reasons, I'm looking for replacements to Guide's
comet data. If I can find something (or, perhaps, create my own),
it's possible that this and other problems can be evaded. There are a
variety of sources for comet elements and magnitude parameters, but
each has some rather serious drawback. (JPL provides comet elements for
objects since 1994, but without SOHO comets or magnitude parameters.
MPC provides elements and magnitude parameters, but only for "currently
visible objects." I have a dataset of pre-1994 comets, but with no
epochs given. I also have, separately, a list of SOHO comet elements.)

-- Bill