Definitions for "Arc second"
Keywords:  sixtieth, angular, minute, degree, dime
An arc second is equal to one-sixtieth of an arc-minute (60th of a degree).
The prefix, arc, is used solely to differentiate this angular measurement from a second of time. By convention, it is 1 part in 1,296,000 of a circle; or 1 part in 3,600 of a degree; or 0.0002778 degree.
1/60 of an arc-minute, which equals 1/60 of a degree. Since there are 360 degrees in a full circle, there are 1,296,000 arc-seconds in a full circle.