The gradian (gon), also called the grad, divides a right angle into 100 equal parts, making a full circle 400 gradians. It is used primarily in surveying and some European military mapping systems, where the base-100 system simplifies decimal calculations. One gradian equals exactly 0.9 degrees.

The arcsecond (″) equals 1/3,600 of a degree, providing extremely fine angular resolution for astronomy, optics, and satellite imaging. The Hubble Space Telescope has a resolution of about 0.05 arcseconds, and stellar parallax measurements use milliarcsecond precision. One arcsecond equals 1/3600 degree or about 0.00000485 radians.