SI-X FORBIDDEN EMISSION IN NGC-1068 AND NGC-7469

This Letter presents the first observation of [Si x] emission in a cel estial object other than the solar corona. The detected line at 1.430 mu m is present in the spectra of both NGC 1068 and NGC 7469. The ioni zation potential of Si x is 401.4 eV, which makes this one of the high est ionization energy lines observed in active galactic nuclei. The li ne falls in a region of high telluric absorption that requires a fortu itous combination of redshift and abnormally dry observing conditions to observe.