Collaborative experiment: Magnetic inclination and declination.

[jonas.persson]

I have tasked students with finding the magnetic inclination and declination as a project at my university. The students are not allowed to use any compasses or compass apps, as these are corrected for this effect. I hoped that someone would use the sun as a way to find the directions, the sun being in the local south around noon. Not many did that.
However, the problem may be rephrased so that you use the sun and find the inclination and declination, as you need the time and the sun's position in the sky, similar to the Suntrace project using phyphox. 
So, using a straw or the shadow, and align the phone with the sun, then send the position and time(UTC) to a server together with the readout of the magnetometer and it will be possible to calculate the inclination/declination, from the sun's position in the sky (calculated), post it on the server and send the result to the user in phyphox. In this way, it will be possible to build a map of variations and give users local values.

On paper, this seems doable, but I might have missed some issues. Is this possible, and is it worth doing, and who would be interested in collaborating?

There exists a project mapping the horizontal and vertical magnetic components (https://www.ncei.noaa.gov/products/crowd...netic-data), but as far as I know, nothing on the inclination and declination.

[Jens Noriʇzsɔɥ]

[I had to check for alternatives to finding north (south)]

I like the simplicity of your approach with the sun. “Technical” solutions could be using GPS (the heading while moving is relative to “True North”, however, some speed is required for sufficient accuracy). Smartphones could also give you “True North”, this might utilise declination maps, though, so it's likely not something wanted.

At the moment, the angle “Direct α” in the “attitude” experiment, https://phyphox.org/wiki/index.php/Attitude_sensor, is relative to magnetic North. We are currently checking if we could provide the means in phyphox to obtain “True North” instead.

I agree that it looks doable and it looks like a nice network/crowd experiment. You certainly need to give some instructions on where –or where not– to measure the magnetic field. Typical school and university tables, for instance, have an iron construction underneath the table top that puts the magnetometer off. There is also the internal calibration of the raw data magnetometer, so overall accuracy is something that should be considered…

I'll check in our next group meeting what others think about your idea.

[jonas.persson]

One of my intentions is to make pupils aware of how we once used the sun for navigation. Thus, the project focuses on determining the magnetic inclination and declination and on how to use the sun for navigation. This way, it is possible to include other subjects in a school project.

I am on a sabbatical in Uppsala right now, and Anders Celsius (with the temperature scale), who was a professor in astronomy there, did measurements of the magnetic inclination and declination and whether it was influenced by auroras. They built a special house for that purpose without any metal.