Optical Spectra of the Type Ia Supernova 1998aq

We present 29 optical spectra of the normal Type Ia SN 1998aq, ranging from 9 days before to 241 days after the time of maximum brightness. This spectrocopic data set, together with photometric data presented elsewhere, makes SN 1998aq one of the best observed Type Ia supernovae at optical wavelengths. We use the parameterized supernova synthetic-spectrum code SYNOW to study line identifications in the early photospheric-phase spectra. The results include evidence for lines of singly ionized carbon, at ejection velocities as low as 11,000 km s -1 . Implications for SN Ia explosion models are discussed.