Here we present 1701 light curves of 1550 unique, spectroscopically confirmed Type Ia supernovae (SNe Ia) that will be used to infer cosmological parameters as part of the Pantheon+ SN analysis and the Supernovae and
H0 for the Equation of State of dark energy distance-ladder analysis. This effort is one part of a series of works that perform an extensive review of redshifts, peculiar velocities, photometric calibration, and intrinsic-scatter models of SNe Ia. The total number of light curves, which are compiled across 18 different surveys, is a significant increase from the first Pantheon analysis (1048 SNe), particularly at low redshift ( z). Furthermore, unlike in the Pantheon analysis, we include light curves for SNe with z< 0.01 such that SN systematic covariance can be included in a joint measurement of the Hubble constant ( H0) and the dark energy equation-of-state parameter ( w). We use the large sample to compare properties of 151 SNe Ia observed by multiple surveys and 12 pairs/triplets of SN siblingsSNe found in the same host galaxy. Distance measurements, application of bias corrections, and inference of cosmological parameters are discussed in the companion paper by Brout et al., and the determination of H0 is discussed by Riess et al. These analyses will measure wwith 3% precision and H0 with 1 km s1 Mpc1 precision.