Title: Characterization and Photometric Performance of the Hyper Suprime-Cam Software Pipeline,
Abstract: The Subaru Strategic Program (SSP) is an ambitious multi-band survey using
the Hyper Suprime-Cam (HSC) on the Subaru telescope. The Wide layer of the SSP
is both wide and deep, reaching a detection limit of i~26.0 mag. At these
depths, it is challenging to achieve accurate, unbiased, and consistent
photometry across all five bands. The HSC data are reduced using a pipeline
that builds on the prototype pipeline for the Large Synoptic Survey Telescope.
We have developed a Python-based, flexible framework to inject synthetic
galaxies into real HSC images called SynPipe. Here we explain the design and
implementation of SynPipe and generate a sample of synthetic galaxies to
examine the photometric performance of the HSC pipeline. For stars, we achieve
1% photometric precision at i~19.0 mag and 6% precision at i~25.0 in the
i-band. For synthetic galaxies with single-Sersic profiles, forced CModel
photometry achieves 13% photometric precision at i~20.0 mag and 18% precision
at i~25.0 in the i-band. We show that both forced PSF and CModel photometry
yield unbiased color estimates that are robust to seeing conditions. We
identify several caveats that apply to the version of HSC pipeline used for the
first public HSC data release (DR1) that need to be taking into consideration.
First, the degree to which an object is blended with other objects impacts the
overall photometric performance. This is especially true for point sources.
Highly blended objects tend to have larger photometric uncertainties,
systematically underestimated fluxes and slightly biased colors. Second, >20%
of stars at 22.5< i < 25.0 mag can be misclassified as extended objects. Third,
the current CModel algorithm tends to strongly underestimate the half-light
radius and ellipticity of galaxy with i>21.5 mag.