I’m starting in on implementing RFC-605, which has been adopted but dormant for five years. This will redefine the FIELD_ANGLE coordinate system for LATISS and DECam by flipping the x-axis relative to the FOCAL_PLANE coordinate system.
This will also affect any third-party obs_* packages that set wcsFlipX=Truein their raw formatter; that flip will need to be moved into the camera geometry definition and removed from the raw formatter class.
If there is any code in the stack (or adjacent packages) that this might break without tripping any tests in CI, please let me know.