absolute magnitude

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The intrinsic magnitude of a celestial body computed as if viewed from a distance of 10 parsecs, or 32.6 light-years.

Wiktionary

1. n. astronomy The intrinsic luminosity that a celestial body would have if viewed from a distance of 10 parsecs or 32.6 light years.

WordNet 3.0

1. n. (astronomy) the magnitude that a star would have if it were viewed from a distance of 10 parsecs (32.62 light years) from the earth