SkyKatana : masks in a pipeline way

SkyKatana is a package to construct and maniputate boolean spatial masks on the celestial sphere covering tens of thousands of square degrees. Starting from (i) a list of geometric shapes, (ii) an input catalog of sources, or (iii) any healsparse map, Skykatana creates pixelized masks in healsparse format with the purpose of excluding areas due to various effects such as bright stars, extended sources, regions of high extinction, bad seeing, etc.

  We call these masks stages, which are stored in a pipeline object along with metadata.

  Stages can be logically combined into a "final" mask by performing unions, subtractions and intersections.

  For each stage you can quickly generate random points, visualize its MOC (Multi-Order Coverage map), overlay catalogs or geometrical shapes, and apply the mask to an arbitrary catalog to restrict to sources located within the mask.

For creating bright star masks, SkyKatana has special methods to query and pixelate large online catalogs in HATS/LSDB format (e.g. Gaia), running in systems with limited memory resources. For example, in the Rubin Science Platform (RSP) it can create a completely customized star mask over 5000 deg² in just a few minutes.

Although mainly designed to work with the upcoming half-sky dataset of the Vera Rubin Observatory, it is flexible to accomodate the particular details of other surveys such as the the Nancy Grace Roman Telescope, the Subaru HSC-SSP, and most wide-field surveys.