An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The portion of the electromagnetic spectrum that is permitted to pass through an electronic device, such as a radio telescope detector. The term refers to either a wavelength interval or a frequency interval.

Bandwidth, from → band + → width.

Bândpahnâ, from bând, → band, + pahnâ, → width, from pahn "wide," → broad.

The angle between the two directions in the main beam at which the power response has fallen to half its maximum value. → beam efficiency.

From → beam + → width.

Tâbe-pahnâ, from tâbé, → beam, + pahnâ "width," → broad.

The width of the lit area of the → Moon measured along the Moon's diameter.

→ crescent; → width.

1) A measure of the → strength of a → spectral line. The equivalent width is the width of a → rectangle centered on a spectral line that, on a plot of → intensity against → wavelength, has the same → area as the line.
2) The width-integrated → optical depth of a → planetary ring. For rings with very small optical depths, the equivalent width is very nearly equal to the equivalent depth (Ellis et al., 2007, Planetary Ring Systems, Springer).

→ equivalent; → width.

The full width of a → profile (spectral line or a cross-cut in an image component) at half-maximum intensity.

→ full; → width; → half; → maximum.

Pahnâ, → width; nim, → half; bišiné, → maximum.

The angle between extreme points of the main lobe of an antenna pattern where the sensitivity of the antenna is half the value at the center of the lobe. This is the nominal resolving power of the antenna system.

→ half; → power; → beam; → width.

1) The range of frequencies or wavelengths over which radiations are absorbed or emitted in a transition between a specific pair of atomic energy levels. The full width is determined between half-power points of the line.
2) In a laser, the range of frequencies over which most of the beam energy is distributed.

→ line; → width.

The interval of time between two successive pulses. Also called pulse length, pulse duration.

→ pulse; → width.

The width size of the slit which determines the spectral resolution of a spectrograph.

→ slit; → width.

An extent from side to side; breadth; wideness. → bandwidth; → beamwidth; → equivalent width; → slitwidth.

From wide, M.E., O.E. wid (cf. Du. wijd, O.H.G. wit, Ger. weit) + -th a suffix forming nouns of quality or condition, M.E. -th(e); O.E. -thu, -th.

Pahnâ, from pahn "wide, broad," from Mid.Pers. pah(a)n; Av. paθana- "broad, wide, spacious."