Allen's Astrophysical Quantities -

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 Allen's Astrophysical Quantities

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 Allen's Astrophysical Quantities