Fluorescence spectra from the Rydberg A2S+(v = 0) level of NO trapped in Ne, Ar, Kr, and Xe matrixes were obtained for 2 different sites. The main site is characterized by broad A(0,v'') bands (full width at half max. .simeq. 80 meV), blue gas-to-matrix shifts of the 70-300 meV, and by absorption-emission Stokes shifts of 300 meV in Xe to 800 meV in Ne matrixes. The line shapes and Stokes shifts were treated within a configuration coordinate model by a moment anal. A linear and quadratic coupling was invoked with relaxation energies ranging for the excited state from 160 meV in Xe to 540 meV in Ne and for the ground state from 150 meV in Xe to 280 meV in Ne and an increase of the cage radius of 3% in Xe to 15% in Ne. The red site fluorescence shows emission bands with matrix shifts of -140 meV in Xe to 80 meV in Ne and absorption-emission Stokes shifts of 210 meV in Xe to 830 meV in Ne. Red site hot A(v = 1) fluorescence was obsd. Red sites were attributed to local disorder around the mol. in Ar, Kr, and Xe matrixes and to hcp. pockets within the fcc. lattice in the case of Ne matrixes. [on SciFinder (R)]