  We present medium resolution (lambda/Delta lambda = 2500) optical
spectroscopy of SN 1999by in NGC 2841 made around its light maximum. The depth
ratio of the two Si II features at 5800 AA and 6150 AA being R(SiII) approx.
0.63 at maximum indicates that this SN belongs to the peculiar, sub-luminous
SNe Ia. Radial velocities inferred from the minimum of the 6150 AA 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 is
estimated based on the Multi-Color Light Curve Shape (MLCS) method, resulting
in M_V(max)=-18.06+/- 0.1 mag and d = 17.1+/-1.2 Mpc, respectively. An
approximative linear dependence of the luminosity parameter Delta on R(SiII) is
presented.
