Simon find an old flash gun, and mate that to a telescope at the focal plane. Keep that handy and charged up in the obs.
If those twits turn up again take aim carefully (a finder helps) let them have a blast full on and they’ll **** their pants.
I can say a Mecablitz on an old C8 OTA worked superbly.
Optional: precede with a nice amplified sound of the flash charging and the voice of Capt Picard announcing “set phasers to stun”...