New Zealand's magnetic observatory instrumentation

Abstract

New Zealand has been involved in the operation of several magnetic observatories over the last 90 years. The principal ones are Scott Base in the Antarctic, Eyrewell and its predecessors, Amberley and Christchurch, in New Zealand, and Apia in Western Samoa until the end of the 1980s when its operation was taken over by the Western Samoan Government. Maintaining a high standard of results from these observatories has not been easy and each observatory presents its own special problems. The average life of sets of recording instruments has been about 30 years. Until a few years ago, classical variometers based on suspended magnets with optical levers and photographic recording were used at each observatory. They have been replaced with fluxgate-based digital recording systems that have been developed and built in New Zealand. Careful attention to detail has resulted in instruments that have proved extremely reliable and perform at least as well as the classical instruments they replace. Absolute determinations of the magnetic vector are made with a Proton Magnetometer to measure magnitude and a Declination and Inclination Magnetometer to determine direction.