We present multi-band optical photometry of 94 spectroscopically-confirmed Type Ia supernovae ( SN Ia ) in the redshift range 0.0055 to 0.073 , obtained between 2006 and 2011 .
There are a total of 5522 light curve points .
We show that our natural system SN photometry has a precision of \lesssim 0.03 mag in BVr ’ i ’ , \lesssim 0.06 mag in u ^ { \prime } , and \lesssim 0.07 mag in U for points brighter than 17.5 mag and estimate that it has a systematic uncertainty of 0.014 , 0.010 , 0.012 , 0.014 , 0.046 , and 0.073 mag in BVr ’ i ’ u ’ U , respectively .
Comparisons of our standard system photometry with published SN Ia light curves and comparison stars reveal mean agreement across samples in the range of \sim 0.00-0.03 mag .
We discuss the recent measurements of our telescope-plus-detector throughput by direct monochromatic illumination by Cramer et al .
( 14 ) .
This technique measures the whole optical path through the telescope , auxiliary optics , filters , and detector under the same conditions used to make SN measurements .
Extremely well-characterized natural-system passbands ( both in wavelength and over time ) are crucial for the next generation of SN Ia photometry to reach the 0.01 mag accuracy level .
The current sample of low-z SN Ia is now sufficiently large to remove most of the statistical sampling error from the dark energy error budget .
But pursuing the dark-energy systematic errors by determining highly-accurate detector passbands , combining optical and near-infrared ( NIR ) photometry and spectra , using the nearby sample to illuminate the population properties of SN Ia , and measuring the local departures from the Hubble flow will benefit from larger , carefully measured nearby samples .