Datepicker: How to fire an event when a date is selected

Datepicker: How to fire an event when a date is selected

I have a jquery datepicker that is working fine.  I'm using a calendar icon only to start the datepicker and the result (the chosen date) is shown as text - not as an input field.
 
To get this result to show, the user has to click an 'update' function button first, which in my case has nothing to do with the datepicker itself.  I know I can use altField to show the result immediately, but that has drawbacks.
 
So I would like to improve the way it works as follows: when the user picks a date, I want the datepicker to close (which it already does) and the chosen date to show immediately, without the user having to click the 'update' button first.  How do I do that?  I don't like to use altField, as the user can muck around with the result if they want to - it is an input field after all.
 
Any ideas?  Thanks in advance!