The most recent version is the , edited by Arthur N. Cox and published around late 1999. This edition was a major collaborative effort involving over ninety contributors to match the original author's comprehensive scope. It more than doubled the size of previous editions to incorporate newer fields like radio, infrared, and x-ray astronomy, as well as recent developments in cosmology. Allens Astrophysical Quantities 1999 12 28

The primary goal of the book is to provide fundamental astrophysical information in a concise, readily usable format. It saves researchers significant time by offering a centralized source of reliable, curated data, which ensures consistency and reproducibility across different investigations. Key Features and Scope

Covers a vast range of topics including general physical constants, solar system data (Sun, planets, moons), and stellar properties like mass, luminosity, and evolution.

Often referred to as the "astrophysical Bible," (AQ) is a classic reference book containing essential data for professional astronomers, researchers, and students. Originally authored by C.W. Allen and first published in 1955, the text has served as an indispensable handbook for generations. Purpose and Impact

Includes detailed information on the interstellar medium, galaxies, quasars, and cosmological parameters such as the Hubble constant.

While highly technical, it serves as a primary reference for undergraduate and graduate students entering the field of astrophysics. Editions and Evolution