UBVRI photometry and optical spectra of type Ia supernova SN 2003du obtained at the Indian Astronomical Observatory for nearly a year since discovery are presented .

The apparent magnitude at maximum was B = 13.53 \pm 0.02 mag , and the colour ( B - V ) = -0.08 \pm 0.03 mag .
The luminosity decline rate , \Delta m _ { 15 } ( B ) = 1.04 \pm 0.04 mag indicates an absolute B magnitude at maximum of M _ { B } ^ { \mathrm { max } } = -19.34 \pm 0.3 mag and the distance modulus to the parent galaxy as \mu = 32.89 \pm 0.4 .
The light curve shapes are similar , though not identical , to those of SNe 1998bu and 1990N , both of which had luminosity decline rates similar to that of SN 2003du and occurred in spiral galaxies .
The peak bolometric luminosity indicates that \sim 0.9 { M } _ { \odot } mass of ^ { 56 } Ni was ejected by the supernova .
The spectral evolution and the evolution of the Si II and Ca II absorption velocities closely follows that of SN 1998bu , and in general , is within the scatter of the velocities observed in normal type Ia supernovae .

The spectroscopic and photometric behaviour of SN 2003du is quite typical for SNe Ia in spirals .

A high velocity absorption component in the Ca II ( H & K ) and IR-triplet features , with absorption velocities of \sim 20 000 km s ^ { -1 } and \sim 22 000 km s ^ { -1 } respectively , is detected in the pre-maximum spectra of days -11 and -7 .