A measure of a star’s observed brightness (opposed to
→ absolute magnitude); symbol m.
It depends on the star’s → intrinsic brightness, its distance
from the observer, and the amount of → interstellar absorption.
The brightest star → Sirius has an apparent magnitude of
-1.46, while the weakest stars visible with the naked eye in the most
favorable observation conditions have magnitudes of about +6.5. The
stars of magnitudes less than +23 are measured by professional
observatories, whereas those of magnitudes less than +30 by a telescope such as
the → Hubble Space Telescope (M.S.: SDE).
See also: → apparent; → magnitude.
