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The unit of measurement for solid angles; it is equal to the solid angle subtended at the center of a sphere by a portion of the surface of the sphere whose area equals the square of the sphere's radius. Abbreviated sr; sterad.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a unit of measurement for solid angles. It is equal to the solid angle subtended at the center of a sphere by a portion of the sphere’s surface whose area is equal to the square of the sphere’s radius. The abbreviations used for the unit are sr and sterad. The solid angle of a sphere at its center is 4π steradians.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Cylindrical irradiance is less directional than irradiance; it includes UV radiation over essentially 47[pi] steradians; that is, all of the possible directions from which UV rays might originate are included.
Legacy Whisper ($12,900, price includes a dedicated Steradian processor) Reviewed by WCH in Issue 73.
The units of radiance are W/[m.sup.2]sr where sr (steradians) are solid angle units (5).
Later, I received a production version of the Steradian. The box was still black, but it was now much more attractive.
The number of photoelectrons per steradian per unit light flux, [dN.sub.v]/d[ohm] is proportional to the differential cross section and hence we can recast the above equation into one that refers to the measurable parameters of the experiment:
The Steradian Processor: The Whispers come with a dedicated version of the Steradian electronic processor, somewhat similar to the Steradian unit that KWN described in his review of the Legacy Focus speakers, but with an algorithm especially designed for the bass characteristics of the Whispers.
Thus, it is normally necessary to consider threats from the complete sphere surrounding the aircraft, which is called "4 p steradian coverage" as shown in Figure 2.
The specified frequency was chosen to be at the peak of the V([lambda]) distribution (555 nm) and the factor 1/683 watts per steradian was chosen based upon the best estimate at that time of the freezing point of platinum.
If you absolutely insist on spending six grand, the Legacy Focus speakers with Steradian processor offer an overall combination of bass performance, dynamic capability, mid an ability to match to various rooms that are unmatched at this price point.
I have become quite spoiled by the Legacy Focus speakers and their associated Steradian environmental processor, which form an admittedly quite expensive ($5,000+) loudspeaker system.