  We present an L-band spectrum of the Ultraluminous Infrared Galaxy IRAS
19254-7245 (the Superantennae), obtained with VLT-ISAAC. The high signal to
noise ratio allows a study of the main spectral features with unprecedented
detail for an extragalactic source. We argue that the main energy source in the
IR is an obscured AGN. This is indicated by the low equivalent width of the 3.3
micron PAH feature, the broad absorption feature at 3.4 um, and the steep
continuum at lambda>3.7 um (f_lambda ~lambda^(2.7)). The substructure of the
3.4 um absorption feature indicates that the absorption is due to hydrocarbon
chains of 6-7 carbon atoms.
