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MOC - HEALPix Multi-Order Coverage map
Version 1.0

IVOA Note 12 April 2012

Interest/Working Group:
Thomas Boch, Tom Donaldson, Pierre Fernique, Wil O'Mullane, Martin Reinecke, Mark Taylor
Pierre Fernique


This note describes a simple and powerful method to specify sky regions. The goal is to have a way for providing very fast comparisons and data access methods. The principle is based on HEALPix sky tessellation. It boils down to defining a list of sky cells, grouped hierarchically. This method has been tested and validated in two tools: Aladin and Topcat, and in a front-end tool for VizieR catalogs.

Status of this document

This is an IVOA Note expressing suggestions from and opinions of the authors.
It is intended to share best practices, possible approaches, or other perspectives on interoperability with the Virtual Observatory. It should not be referenced or otherwise interpreted as a standard specification.

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