libhealpix-java-doc binary package in Ubuntu Focal arm64

 HEALPix is an acronym for Hierarchical Equal Area isoLatitude Pixelization
 of a sphere. As suggested in the name, this pixelization produces a
 subdivision of a spherical surface in which each pixel covers the same
 surface area as every other pixel. It is commonly used to store all-sky
 astronomical images, most famously maps of the cosmic microwave background.
 .
 This package provides documentation for the Java language implementation of
 HEALPix.

Source package