arc second


Also found in: Dictionary, Thesaurus, Medical, Legal, Financial.
Related to arc second: parsec, radian

arc second

(arcsec; second of arc) Symbol: ″. A unit of angular measure equal to 1/3600 of a degree. It is used, for example, to give the apparent diameter of objects, the angular separation of binary stars, and the proper motion and annual parallax of stars. An arc minute, symbol: ′, is 60 arc seconds, i.e. 1/60 of a degree. The full Moon is about 30′ in diameter.
References in periodicals archive ?
Arc Second's president, Ed Barrientos, likened the system to a robotic theodolite.
Working range of the system is from 75 metres to infinity with a resolution of 0.7 arc second and a clear aperture of 178 mm.
Arc Second, Inc., Dulles, Va., a provider of mobile CAD software solutions, has announced the beta release of DWFView(TM), a custom add-in designed for use with PocketCAD PRO 4.0.
Tests show that, in orbit, the mirror assembly will be able to focus approximately 70% of X-rays from a source to a spot less than one-half an arc second in radius.
By adjusting individual tiles of the segmented mirror 100 times a second, the telescope is expected to produce images with a resolution as sharp as 0.04 arc second in the near infrared.
Four-year-old highlights were topped by a King George win from Wings Of Desire that at the time was widely attributed to a clever front-running ride from Ryan Moore, and a brilliant defeat of old rival Flintshire in the Breeders' Cup Turf, but his Arc second to stablemare Found was another great effort and a career-best on Racing Post Ratings.
shows two distinct sources barely 1 arc second apart [that] coincide with radio sources detected earlier at the Very Large Array....
The Signum RESM optical angle encoders make an ideal fit for direct drive rotary motors, eliminating position error and backlash while delivering speeds to over 3,600 rev/min, accuracy to [+ or -] 0.5 arc second, plus resolution and repeatability to 0.02 arc second.
Last year's Arc second Mubtaker was expected to head our raiding party in the valuable contest at Baden Baden, with Warrsan and the Kieren Fallon-ridden Gamut playing supporting roles.
A double enveloping gear on the rotary table and mechanical disk brake with 12 pads ensure accuracy of [+ or -] 5 arc sec and repeatability of [+ or -] 1 arc second. The rotary table motor features a ratio 180:1 and operates at 17 rpm.
Its operating specifications include an angle range of [+ or -][degrees]C, resolution of 1 arc second and null repeatability of [less than or equal to]5 arc seconds.
Before the repairs, the telescope could only focus about 12 percent of light from celestial objects -- far less than its design goal -- into a radius of 0.1 arc second. In comparison, Hubble's new Wide-Field and Planetary Camera, which has built-in optics to correct for the telescope's optical flaw, focuses 60 to 70 percent of light into a circle of that radius, says Hubble senior scientist David S.