Install libhealpix-java-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libhealpix-java-doc
Description:
HEALPix representation of spherical data - Java documentation
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.
Homepage: http://healpix.sourceforge.net
Version: 3.31-2
Section: universe/doc