### radio source counts

**(source counts)**
(using radio source population characteristics to determine curvature)

In cosmology, **radio source counts** (or just **source counts**)
is a method of detecting the curvature of space. In a flat,
Euclidean space, a uniform distribution of radio sources
(the scale of interest being cosmological distances, i.e., radio galaxies),
with the same distribution of luminosities throughout, implies
a certain pattern to the count of detectable sources at each luminosity:

log N = -1.5 log S

- S - a given flux density.
- N - number of sources at least as bright as S.

Divergence from this gives information about the geometry of the
universe over time.

(*cosmology,radio*)
http://en.wikipedia.org/wiki/Source_counts

https://ned.ipac.caltech.edu/level5/Sept04/Condon/Condon4_2.html

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