An arcsecond, also called a second of arc or arc second, is a unit of angular measure equal to 1/60 of an arcminute, or 1/3600 of
a degree. The arcsecond is denoted 
(not to be confused with the symbol for inches).
Arcsecond
See also
Arcminute, DegreeExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Arcsecond." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Arcsecond.html