Detection of forbidden Si VI 1. 962 microns and new observations of infrared H, forbidden Fe II, and H2 line emission in the Seyfert galaxy NGC 1068

Measurements of several infrared lines in NGC 1068 are presented, including the forbidden Si VI transition at 1.962 microns which is detected for the first time in an extragalactic object. This line is among the brightest IR features (about 5 times stronger than H2 2.121 microns), is broad (Delta-v of about 1100 km/s), and has a profile similar to He I 1.083 microns. The possibility of using the forbidden Si VI line to trace Seyfert activity and the origin of the H, forbidden Fe II, and H2 lines are briefly discussed. 23 refs.