skies
The skies directory contains blank sky locations derived
at the pixel-level from the Legacy Surveys images. Sky locations
are stored in files that are grouped by (nested) HEALPixel number
in filenames that resemble skies-hp-{HP}.fits, where HP is
the HEALPixel number.
The skies directory may also contain an unpartitioned sub-directory.
This exists because the sky locations are originally generated in
Legacy Surveys bricks before being re-partitioned into HEALPixels.
The unpartitioned sub-directory contains files assembled according to
which bricks occupy each HEALPixel rather than by which sky locations
occupy each HEALPixel.
Subdirectories and files: