2001AJ....121.3127V

We present medium-resolution (λ/Δλ~2500) optical spectroscopy of SN 1999by in NGC 2841 made around its light maximum. That the depth ratio of the two Si II features at 5800 and 6150 Å are R(Si II)~0.63 at maximum indicates that this SN belongs to the peculiar subluminous Type SNe Ia. Radial velocities inferred from the minimum of the 6150 Å trough reveal a steeper decline of the velocity curve than expected for normal SNe Ia, consistent with the behavior of published VRI light curves. A revised absolute magnitude of SN 1999by and distance to its host galaxy NGC 2841 are estimated based on the multicolor light-curve shape (MLCS) method, resulting in M_V(max)=-18.06±0.1 mag and d=17.1±1.2 Mpc, respectively. An approximate linear dependence of the luminosity parameter Δ on R(Si II) is presented.