SAM Viby facilitates Speake & Co Llanfapley FGM-3 fluxgate sensors for measuring the local magnetic field.
The magnetometer is located in Viby (Sollentuna), about 15 km North of Stockholm.
Geographic coordinates: 59o27min N 17o54min E
Geomagnetic coordinates (2017): 57.69oN, 106.22oE
Magnetic declination: 5 57.60' East (IGRF-12 Model , 2015)
Annual Change (minutes/year): 10.3 '/y East
Construction and installation of the instrument
After a successful maintenance of SAM
Haimhausen, a magnetomete which I am running 20 km north of Munich,
Germany, I decided to install a magnetometer close to my residence north of
Stockholm. Just some kilometers off the 60th parallel, this location with about
10 northern light occurrences every seasoa seems well suited for geomagnetic measurements.
Ralf Pitscheneder generously donated his 2-axis SAM magnetometer for further
use as SAM Viby. This magnetometer was operated from 2004-2010 in Munich as
well. We have brought it to Sweden and installed it end of 2016. The device now
takes measurements in a preliminary, yet stable configuration.
The two magnetic field sensors were reused and installed in a 50-liter
cartboard box in my storage, which features reasonable temperature stability (the magnetic field sensors are quite sensitive to temperature changes on the 0.1 degree Centigrade level).
The location is as magnetically quiet as a suburban neighborhood can be, but
SAM Viby is powerful software tools to counteract effects of man-made
disturbances on the measurements. Recently, the observatory was fitted with
temperature sensors, and I have plans to improve temperature insulation of the
observatory using styrofoam detector holders and embedding the setup in an aluminum shield filled with styrofoam spheres (which are produced by a local chap).
On the scientific side, the observatory currently reads the two horizontal
components of the Earth's magnetic field. The accuracy of the relative
measurements is given by ±1-2 nT (sensor accuracy), and probably ≈5 nT
man-made disturbances. Relative measurements are relevant for producing alerts for northern lights observations.
SAM Viby also does absolute magnetic field measurements. These are currently calibrated using the WMM2015 model which is evaluated on daily basis. The model bears uncertainties of ≈135 nT in each coordinate.
An immediate upgrade will be to equip SAM Viby with a third fluxgate sensor as to measure also the horizontal component of the magnetic field.