Northern lights are beautiful and simultaneously interesting. At night time, you might go out and see a wonderful light show. Or during the day you may very well be surprised by radio propagations. But when must you go out? or listen in to the radio? You need to be aware of the current aurora activity in your area, real time. Aurora is measured using a magnetometer. Sensors are available, one in particular is the FG-3+ sensor by It is sensitive and inexpensive. Buying the sensor is easy, but what’s next? We need an interface!


Above is AU-100 an experimental, proof of concept, device which interfaces with the FG3 sensor. It has a display showing the current readings from the magnetometer. It has a user interface to set some configurations and a wifi module.

3 leds indicate the current activity. Green / Yellow / Red. Full scale alarm is set at 1nT/second. Which in my location is a good setting. This setting can be configured.

Live data

Currently this device is online, and uploading data to

Sensor location

The magnetometer sensor should be places ‘far away’ from any magnetic disturbances. Far in this case means at least 50 meters away from any moving metal objects (cars!) bikes or what not. The sensor must be placed in a temperature stable environment. This practically means 40cm below the ground, where the temperature is stable enough. I’ve made a separate board with power supply and a transmitter to send the signal back to the AU-1. A typical ethernet cable is used between the AU-1 and the sensor board.

Current status of this project

One device is active and sharing data. No active developments planned, but interested to continue this project.

If you think I should continue to develop this project, please let me know your thoughts and fill out this form!

    How should it connect to the internet

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    Event 31 Dec 2020

    On the night from 30 to the 31st of Dec 2020 a short but nice event was captured, here a comparison of the AU-100 and the official measurements by the Finnish Meteorological Institute,

    Nurmijärvi Geophysical Observatory.
    Aularma AU-100 Vihti

    11 March 2022

    Project is still running, however I changed the page to be at