  We have searched for Type Ia supernovae (SNe Ia) in the local (d < 60 Mpc)
Universe using Northern Sky Variability Survey (NSVS) data collected from the
nightly optical surveys of the Robotic Optical Transient Search Experiment}
(ROTSE) Telescope. It was hoped that SNe Ia would provide a means to find
previously-unknown low surface brightness (LSB) galaxies or displaced stars
that would otherwise be very difficult to detect. The ROTSE data allowed us to
survey 19,000 square degrees at declinations north of 0 degrees, but we did not
find a single SN Ia in a period of time covering roughly one year. Using known
SNe Ia rates in bright galaxies, we set an upper limit on the optical
luminosity density, L_B, of LSBs in the local Universe. Using mean LSB baryonic
and dynamical mass-to-light ratios, we find 95% upper limits for LSBs of L_B
\le 2.53 x 10^8 L_{B, solar} Mpc^{-3}, Omega_b \le 0.0040, and Omega_m \le
0.036. We conclude that LSBs and displaced stars are not a major constituent of
matter in the local Universe.
