Dealing with "Strange Magnetic Field"

If you are seeing the message "Warning: Strange magnetic field" then firstly, "Don't Panic"!

This message is shown when the difference between the detected field strength and the expected Earth's magnetic field strength is higher than usual at your location. The sensors are quite sensitive, so the difference is often negligible for day-to-day activities. But it could be substantial for navigation / sky map pointing.

You can try out some suggestions given below. But first, let's understand how SkEye works.

The Magnetometer and the Earth's Magnetic field

Whenever SkEye is in automatic scrolling mode, SkEye gathers data from two or three sensors in your Android device: the accelerometer, magnetometer and gyroscope (if available).

The magnetometer measures the ambient magnetic field around the device, similar to a magnetic compass needle. Ideally, the device is surrounded by only the Earth's magnetic field which helps to figure out the direction accurately.

However, in practice, there can be other sources of magnetic fields too. For example, these could be:
  • Strong permanent magnets such as those in loudspeakers.
  • Electronic equipment such as laptops.
  • Transmission wires
  • Steel OTA of a telescope
These magnetic fields interfere with each other and it becomes impossible to measure the Earth's magnetic field accurately.

When SkEye detects that the measured magnetic field strength does not match the expected strength of the Earth's magnetic field at your location, it shows the warning: "strange magnetic field". If the measured strength is very different from expected, then the message shown is: "extremely strange magnetic field".


There are couple of things you can do if you see this message:
  • Try calibrating the magnetometer. A simple wave of the device at arm's length will often calibrate it.
  • Try observing from a different location. You might have to go outdoors, far from interfering gadgets, transmission wires, etc.
  • Check if your device has a cover with a magnetic button. You might have to discard such a cover.
  • Check if you have specified your location correctly. The strength of the Earth's magnetic field is not constant; it varies by time and place.
  • Check the system date on your device.
  • If nothing else works, the magnetometer might be faulty. If you have access to another device, try running SkEye on it from the same location.

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