A little electronics help

I am trying to end some fumbling with flashlights at the telescope by rigging some led lights to illuminate my setting circles.

I have made some simple lights from a 2 AA battery holder and an LED. I want to attach these to the mount, and then by pushing a button have them illuminate for a timed period, say 15 to 20 seconds and then go out.

I could use some help finding the appropriate switch. Can some one guide me to a suitable switch component to make this work? My knowledge of electronics is basic at best, so any other information I should have to make this work would be appreciated as well.

Thanks!

A brute-force method would be to wire-up a
555 IC with a resistor, capacitor, and
push-button switch. Try to google
"555 one-shot timer"
for some ideas. For example see
http://www.electronics-tutorials.com/devices/555.htm
This is sometimes called a "monostable timer."

Another way would be to find some
off-the shelf gadget at Wal-Mart for 50 cents
that does roughly what you want already.