libhealpix-cxx-dev binary package in Ubuntu Focal amd64

 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 the static library and headers for the C++ language
 implementation of HEALPix. The C++ library provides input/output, basic
 spatial operations such as conversion between spherical coordinates and
 HEALPix pixels, and also sophisticated spatial operations such as querying
 cones or polygons, as well as upsampling/downsampling, smoothing, and fast
 spherical harmonic transforms.

Source package