The electronic spectrum of C17H12N+, phenanthrene with a side chain, was measured in the gas phase at a vibrational and rotational temperature of similar to 15 K in an ion trap using a resonant multiphoton dissociation technique. The C17H12N+ structure was produced in a chemical ionization source and identified by a comparison with theoretical calculations of stable structures and excitation energies. The (3), (2), (1) (1)A <- X (1)A electronic transitions of this nitrogen-containing aromatic species with 30 atoms have origin band maxima at 23?586 +/- 1 cm(-1), 16 120 +/- 50 cm(-1), and 14 519 +/- 30 cm(-1). Distinct vibrational structure in the (3) (1)A state is observed, and assignments are made. Astronomical aspects are considered.