time axis question

["David S. Dimitriou" <dsdimitr@xxxxxxxxxxxxxxxxxxxxxxx>]

tia
Heres my question:
I have a plot of a time series of arctic ice concentrations with % on y-axis
and time on x-axis. I put this in the lower portion of a movie of arctic ice
concentrations. Is there a way to indicate along the curve of the time series
the date. What I want is the value on the time series curve which corresponds
with the timeframe being displayed in the movie to be marked. So I would have a
dot/symbol/whatever moving from left to right on top of the time series curve.
thanks again,
dave dimitriou