Over the past twenty years, our magnetometers have become a standard in magnetic observatory measurements based on sensitivity, high absolute accuracy, minimal drift, high resolution and other factors. This expertise has translated into some of the world’s finest instruments for base magnetometers and observatory magnetometers. Here, we talk briefly about base stations and more about observatory systems as they are highly linked in their innovation and development.
The dIdD Suspended Magnetometer for accurately measuring the changing Declination and Inclination of the Earth’s Field In the past, magnetic observatories relied on a combination of Overhauser, fluxgate and theodolite instruments for obtaining measurements. dIdD was enhanced significantly with the development of the Suspended dIdD system. Declination & Inclination Vector Magnetometer Systems latest development in this field is the Absolute Magnetic Declination & Inclination (DI) Meter. This instrument is being designed to provide a measurement of Declination and inclination at a given location on the globe.
This system is an adaptation of the dIdD vector magnetometer, this system will eliminate the need for a theodolite, by determining declination and inclination (not just changes in inclination / declination). This instrument is an Overhauser magnetometer with 2 sets of bias coils (horizontal & vertical) in the magnetic north plane. The new instrument (DI) simplifies setting observatory magnetometers by eliminating the need for fluxgate magnetometers and thermal insulating structures as before, and now a theodolite system.
Observatory Applications As described by the Israeli Nuclear group, Soreq, the dIdD is a vector magnetometer offering monitoring of the inclination and declination as well as total intensity of the earth’s magnetic field. Resolution is 0.01 nT with a recording interval of 5 samples per second. The Suspended dIdD instrument provides key benefits;
Many magnetic observatories today rely on a combination of scalar, fluxgate and theodolite instruments for obtaining measurements. Research installations engaged in volcanology applications are also using scalar magnetometers for stationary work. GEM’s Overhauser GSM-90 EUROMAG is particularly suited to these applications (and volcanology). This is a standard magnetometer without a display screen that can be operated via computer. Observatory and Volcanology Applications Up until about 10 years ago, magnetic observatories around the globe used fluxgate magnetometers as their primary tools to monitor the earth’s magnetic field. But fluxgates have the disadvantage that they must be periodically calibrated to maintain the level of absolute accuracy that is so important in observatory research. By using an Overhauser magnetometer (EUROMAG) together with a fluxgate magnetometer, both total field and field direction information can be collected with a very high degree of absolute accuracy. (Users may also be interested in the GEM’s new Suspended dIdD magnetometer which can be accessed via the Vector Magnetometers product page.)
Increasingly, researchers are looking in to the applications of magnetics alone or in combination with seismic or radon measurements as means of monitoring geohazards (i.e. for earthquake prediction). It also has military applications. GEM’s solution for these types of installations is the Potassium SuperGrad. This special gradiometer is a system based on the Optically Pumped Potassium instrument – a unique technology that was developed in response to the United States Geological Survey’s need for an ultra-high sensitivity magnetic gradiometer. GeoHazard Applications The SuperGrad is a three axis total field magnetometer/gradiometer of choice for customers who require: Superior gradiometer sensitivity High absolute accuracy Almost no orientation errors Reliability The SuperGrad is currently being employed for earthquake studies in the vicinity of the Dead Sea Rift, Israel in combination with an integrated radon measuring system. The Integrated SuperGrad/Radon (ISGR) system was developed in conjunction with ISORAD. The Geological Survey of Israel and the Israel Survey have also been key participants in the realisation of an initial working and tested product.