We present the first public version (v0.2) of the open-source and community-developed Python package, Astropy. This package provides core astronomy-related functionality to the community, including support for domain-specific file formats such as Fle
xible Image Transport System (FITS) files, Virtual Observatory (VO) tables, and common ASCII table formats, unit and physical quantity
This document describes a convention for compressing n-dimensional images and storing the resulting byte stream in a variable-length column in a FITS binary table. The FITS file structure outlined here is independent of the specific data compression
algorithm that is used. The implementation details for 4 widely used compression algorithms are described here, but any other compression technique could also be supported by this convention. The general principle used in this convention is to first divide the n-dimensional image into a rectangular grid of subimages or tiles. Each tile is then compressed as a block of data, and the resulting compressed byte stream is stored in a row of a variable length column in a FITS binary table. By dividing the image into tiles it is generally possible to extract and uncompress subsections of the image without having to uncompress the whole image.
