  We present a set of 11 type Ia supernova (SN Ia) lightcurves with dense,
pre-maximum sampling. These supernovae (SNe), in galaxies behind the Large
Magellanic Cloud (LMC), were discovered by the SuperMACHO survey. The SNe span
a redshift range of z = 0.11 - 0.35. Our lightcurves contain some of the
earliest pre-maximum observations of SNe Ia to date. We also give a functional
model that describes the SN Ia lightcurve shape (in our VR-band). Our function
uses the "expanding fireball" model of Goldhaber et al. (1998) to describe the
rising lightcurve immediately after explosion but constrains it to smoothly
join the remainder of the lightcurve. We fit this model to a composite observed
VR-band lightcurve of three SNe between redshifts of 0.135 to 0.165. These SNe
have not been K-corrected or adjusted to account for reddening. In this
redshift range, the observed VR-band most closely matches the rest frame
V-band. Using the best fit to our functional description of the lightcurve, we
find the time between explosion and observed VR-band maximum to be
17.6+-1.3(stat)+-0.07(sys) rest-frame days for a SN Ia with a VR-band Delta
m_{-10} of 0.52mag. For the redshifts sampled, the observed VR-band
time-of-maximum brightness should be the same as the rest-frame V-band maximum
to within 1.1 rest-frame days.

Astrophysics