### full width at half maximum

**(FWHM)**
(a measure of the width of a hump-shaped curve)

**Full width at half maximum** (**FWHM**) is one measure of the width
of a hump or valley in the plot of a continuous function. "Maximum"
is taken as the maximum amount above (or below, i.e., "maximum depth")
the value of the function on either side of the hump or valley, and
the value is the width in the "X direction" between points on this
hump or valley where the function is half the difference between
this maximum (or maximum depth) and the value outside the hump/valley.

The Gaussian function with its **bell curve** is a function with
such a hump. Astrophysics uses the measure as a means to quantify
the width of a spectral line, e.g., in formulae that relate the
width to other quantities. It is also used to specify passband
specifications, sensitivity functions and other similar functions.

(*mathematics,measure*)
http://en.wikipedia.org/wiki/Full_width_at_half_maximum

**Referenced by:**

B

bandwidth

I band

K band

line broadening

R band

seeing

Strömgren photometric system

U

V

index