Hi folks,

Sorry for the long silence! I've come back to find a large batch of
e-mails; I should be clearing the backlog in a bit.

Guide just shows the tail pointing away from the sun, which is
usually a good guess. It's been suggested to me that the ion tail
usually points away from the sun, but that the dust trail usually
points along the line of variation. (That is, solar radiation pressure
knocks off the dust and pushes it out slightly; that results in the
dust grains traveling along the same orbit as the comet, but gradually
falling behind it.)

Dunno how much truth there is to this. I'll probably try it out at
some point; if it works, Guide could show both the ion tail _and_ the
dust tail, and probably even a dust tail with the right curve.

-- Bill