We present a measurement of the rate of type Ia supernovae ( SNe Ia ) from the first of three seasons of data from the SDSS-II Supernova Survey .
For this measurement , we include 17 SNe Ia at redshift z \leq 0.12 .
Assuming a flat cosmology with \Omega _ { m } = 0.3 = 1 - \Omega _ { \Lambda } , we find a volumetric SN Ia rate of [ 2.93 ^ { +0.17 } _ { -0.04 } ( { systematic } ) ^ { +0.90 } _ { -0.71 } ( { statistical } ) ] % \times 10 ^ { -5 } ~ { } { SNe } ~ { } { Mpc } ^ { -3 } ~ { } h _ { 70 } ^ { 3 } ~ { } { year } ^ { -1 } , at a volume-weighted mean redshift of 0.09 .
This result is consistent with previous measurements of the SN Ia rate in a similar redshift range .
The systematic errors are well controlled , resulting in the most precise measurement of the SN Ia rate in this redshift range .
We use a maximum likelihood method to fit SN rate models to the SDSS-II Supernova Survey data in combination with other rate measurements , thereby constraining models for the redshift-evolution of the SN Ia rate .
Fitting the combined data to a simple power-law evolution of the volumetric SN Ia rate , r _ { V } \propto ( 1 + z ) ^ { \beta } , we obtain a value of \beta = 1.5 \pm 0.6 , i.e .
the SN Ia rate is determined to be an increasing function of redshift at the \sim 2.5 \sigma level .
Fitting the results to a model in which the volumetric SN rate , r _ { V } = A \rho ( t ) + B \dot { \rho } ( t ) , where \rho ( t ) is the stellar mass density and \dot { \rho } ( t ) is the star formation rate , we find A = ( 2.8 \pm 1.2 ) \times 10 ^ { -14 } ~ { } \mathrm { SNe } ~ { } \mathrm { M } _ { \sun } ^ { -1 } ~ { } % \mathrm { year } ^ { -1 } , B = ( 9.3 ^ { +3.4 } _ { -3.1 } ) \times 10 ^ { -4 } ~ { } \mathrm { SNe } ~ { } \mathrm { M } _ { \sun } ^ { -1 } .