Fluorescent Molecular Hydrogen LineEmission in the Far {

SUMMARY Over 30 lines from the v=3{0, 4{1, 7{3 and 8{4 vibrational series of the hydrogen molecule have been observed from = 7600{8800 A in the reeection nebula NGC 2023, originating from levels up to 41,000 K above ground. This is the rst time that H 2 has been observed in 1 the optical CCD regime and these are the highest excitation lines from the ground electronic state that have yet been detected. The spectrum shows the characteristics expected of UV{ uorescence, although in detail there are some diierences from model predictions. Emission from newly formed molecules in v=4 may have been detected. Strong CI] 8727 A forbidden line emission is also observed, coincident with the H 2 emission, and arising from the same photodissociation region gas.