The personal

error in absolute geomagnetic measurements


(1)Institute of Geophysics, China Earthquake



The fluxgate

theodolite is an instrument which was made up of two parts, fluxgate

sensor and theodolite. And the fluxgate sensor is mounted on top of

the telescope of the theodolite. It was used to measure the magnetic

declination D and inclination I in absolute geomagnetic measurements.

There are many errors in the measurement, for example, Index error,

horizontal-axis error, collimation error, personal error and so on.

Some of them can be eliminated by choosing specific measurement

procedure. So they have no impact on the measurement results. However,

the personal error is difficult to eliminate. Because it may arise

from the observer’s minimum resolution in physiology or reading

error, it may come from the observer’s observation method or skill

and so on. As modern fluxgate has a high precision, usually with 1

second of arc, the personal error effect on the observation result has

become a factor that cannot be ignored. In order to estimate personal

error, an experiment has been done. Several observers who were

proficient in observation were invited to finish this measurement

experiments. The fluxgate theodolite was fixed on the observation

pillar, and the observers took turns to observe it. Finally, the

personal error can be estimated by comparing the observation