Arcsecond
An arcsecond (second of arc), represented by the symbol [math]\displaystyle{ '' }[/math],[1] is a unit of angle used in mathematics and astronomy. An arcsecond is 1/60th of an arcminute (minute of arc),[2] which in turn is 1/60th of a degree.[3] Therefore, an arcsecond is equal to 1/3600th of a degree,[2] meaning that there are 360 × 60 × 60 = 1,296,000 arcseconds in a full circle.
One milliarcsecond (mas) is a thousandth (1/1000th) of an arcsecond. So there are 1,296,000,000 milliarcseconds in a full circle. The red supergiant stars Antares, Betelgeuse,[4] Mu Cephei, VV Cephei A, and VY Canis Majoris all have angular diameters (apparent sizes in the sky) of more than 10 milliarcseconds, when seen from Earth.
Arcsecond Media
Comparison of angular diameter of the Sun, Moon, planets and the International Space Station. True representation of the sizes is achieved when the image is viewed at a distance of 103 times the width of the "Moon: max." circle.
Example ballistic table for a given 7.62×51mm NATO load. Bullet drop and wind drift are shown both in mrad and minute of angle.
Comparison of minute of arc (MOA) and milliradian (mrad).
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Related pages
References
- ↑ "List of Geometry and Trigonometry Symbols". Math Vault. 2020-04-17. Retrieved 2020-08-31.
- ↑ 2.0 2.1 Weisstein, Eric W. "Arc Second". mathworld.wolfram.com. Retrieved 2020-08-31.
- ↑ Weisstein, Eric W. "Arc Minute". mathworld.wolfram.com. Retrieved 2020-08-31.
- ↑ http://www.astroscu.unam.mx/rmaa/RMxAC..37/PDF/RMxAC..37_ohernandez.pdf