  (abridged) - We present arcsecond resolution observations from the VLA of the
satellite line of the hydroxyl molecule (OH) at 1720.53 MHz toward three
Galactic supernova remnants: W28, W44 and IC443. All of our observations are
consistent with a model in which the OH(1720 MHz) is collisionally excited by
H2 molecules in the postshock gas heated by a non-dissociative shock. Supernova
remnants with OH(1720 MHz) maser emission may be promising candidates to
conduct high energy searches for the sites of cosmic ray acceleration.
