In the HSC CCD layout, approximately half of the HSC CCDs are rotated 180 deg with respect to the others, two others have 90 deg rotations and another two have 270 deg rotations. The HSC camera geometry defined a coordinate system where pixel (0, 0) is always the lower-left corner. However, the new camera geometry in the LSST stack does not use this interpretation, preferring to maintain the coordinate system tied to the electronics. As such, accommodations have had to be made for the rotated CCDs on obs_subaru. See
DM-4998 and DM-5107 in particular for details. The need for these accommodations, and the accommodations themselves, should be removed. This entails a re-ingestion of the HSC calibration data files (BIAS, DARK, FLAT, etc.) as well as a redefinition of the defects files in obs_subaru.