Over the past twenty years, GEM has 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.
Both ground and airborne magnetometer surveys require a base station to correct for diurnal magnetic fluctuations related to the solar wind, sunspots and other localized magnetic activity. The survey proceeds with a “rover” or moving magnetometer which is in some way linked to an actively working base station. Links are commonly through time references such as GPS time or alternately, the rover and base can be synchronized in time.
As diurnal corrections have a large effect on the final results, it is essential to have reliable, accurate corrections. GEM provides several systems for base stations including its Overhauser and Potassium series of magnetometers. A Proton solution is also available for less stringent surveys.
Overhauser and Potassium have all of the specifications required to perform to the most stringent surveys. Overhauser is a mid-range instrument with good sensitivity, and is the unit that most users rely on. Potassium is a high-end instrument with excellent sensitivity for the most demanding of specifications. Both of these instruments feature proven long-term stability, good to excellent sensitivity, and high absolute accuracy.
To learn more about base station options from GEM, please access the Base Station Solutions information please click here
As described by the United States Geological Survey, “the Magnetic Observatory system has a relatively short history dating back to the 1800’s. The need for accurate and continuous measurements of the Earth’s magnetic field was recognized early in the field of geomagnetism, both for historical database archives, and for studies of the Sun, the Earth’s interior, and the surrounding space environment.”
Nowadays, magnetic observatories have been set up around the world for the explicit purposes of long – and short-term monitoring of the time-varying magnetic field.
Today’s magnetic installations are typically configured with a vector fluxgate magnetometer (for measuring the three orthogonal components of the geomagnetic field); a scalar magnetometer for measuring the total field intensity, a theodolite (for orienting the vector magnetometer), and a data collection platform for storing data.
Implementations are changing; however, particularly with the advent of GEM’s vector series of magnetometers which allow magnetic inclination and declination as well as their variation in time to be measured very accurately. GEM offers two variations–an Overhauser system and a high sensitivity Potassium system. Both of these offer a novel, suspended technology for increased accuracy and precision.
GEM also continues to offer its powerful scalar magnetometers for clients who cannot yet migrate to a vector solution. GEM’s GSM-90 (EuroMag) is a 3-second sampling (slow) magnetometer available at low cost. The more advanced GSM-90F1 offers Intermagnet-standard measurement at 1 second (5 second average) and 5 second windows.
In addition to scalar and vector magnetometers, the company also offers the SuperGrad 3-axis scalar gradiometer for very high sensitivity measurements–primarily for earthquake research.
For more information on GEM’s special Observatory magnetometers, please click here
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