Measurement[edit]
The smallest precision level for a magnetic field measurement[13] is on the order of attoteslas (10−18 teslas); the largest magnetic field produced in a laboratory is 2.8 kT (VNIIEF in Sarov, Russia, 1998).[14] The magnetic field of some astronomical objects such as magnetars are much higher; magnetars range from 0.1 to 100 GT (108 to 1011 T).[15] See orders of magnitude (magnetic field).
Devices used to measure the local magnetic field are called magnetometers. Important classes of magnetometers include using a rotating coil, Hall effect magnetometers, NMR magnetometers, SQUID magnetometers, and fluxgate magnetometers. The magnetic fields of distant astronomical objects are measured through their effects on local charged particles. For instance, electrons spiraling around a field line produce synchrotron radiation that is detectable in radio waves.