Title: The bright-star masks for the HSC-SSP survey,
Abstract: We present the procedure to build and validate the bright-star masks for the
Hyper-Suprime-Cam Strategic Subaru Proposal (HSC-SSP) survey. To identify and
mask the saturated stars in the full HSC-SSP footprint, we rely on the Gaia and
Tycho-2 star catalogues. We first assemble a pure star catalogue down to
$G_{\rm Gaia} < 18$ after removing $\sim1.5\%$ of sources that appear extended
in the Sloan Digital Sky Survey (SDSS). We perform visual inspection on the
early data from the S16A internal release of HSC-SSP, finding that our star
catalogue is $99.2\%$ pure down to $G_{\rm Gaia} < 18$. Second, we build the
mask regions in an automated way using stacked detected source measurements
around bright stars binned per $G_{\rm Gaia}$ magnitude. Finally, we validate
those masks from visual inspection and comparison with the literature of galaxy
number counts and angular two-point correlation functions. This version
(Arcturus) supersedes the previous version (Sirius) used in the S16A internal
and DR1 public releases. We publicly release the full masks and tools to flag
objects in the entire footprint of the planned HSC-SSP observations at this
address: this ftp URL.