observationsvolym
observationsvolym is the region of space or parameter space accessible to a given set of observations under a specific survey design and instrument sensitivity. In astronomy and cosmology, the term describes the comoving or physical volume within which objects can be detected by a survey, given flux or magnitude limits, sky coverage, and redshift range. The volume depends on cosmology and the instrument’s sensitivity and is central to deriving number densities and luminosity functions from observed counts.
Formally, if a survey covers a solid angle Ω and spans redshifts z1 to z2 with a selection
Examples are common in galaxy surveys such as SDSS and DES, where the survey volume can reach
See also: selection function, completeness, luminosity function, comoving volume.