Objects around bright stars likely have bad photometry and are flagged by the pipeline.  Coupon et al. (2018) used the NOMAD catalog as a reference catalog of bright stars, but we have changed to GAIA DR1.  We flag objects around the GAIA stars within certain radii, where the object detection and photometry are likely affected.  Users can apply a flag cut to construct a catalog of objects with clean photometry.

There are issues with the current masks as summarized in the Known Problems page.  In short, the current masks (left image) are too small and some bright stars are missing the masks.  We have further revised the masks using GAIA DR2 (right image) and these revised masks are being validated within the HSC collaboration.  Once we validate them, we will make an incremental data release to make the masks available to the community.

The revised masks shown on the right are released as part of the incremental release 1. They are available at the database (pdr2_{wide,dud}.masks). They are significantly better than the previous version, but are still not without problems. See the known issue page for details. Note that the bright star mask bits stored in the coadd images are still the old version; if you would like to use the revised version, please use the mask definition files, which are in the standard ds9 region format.