Magnetometer data - What to make of it?

My team and I have just fired a CanSat and are a bit confused about the data we got from our magnetometer(Mag_data.png). We would assume that it should be constant.

We used the 9 Degrees of Freedom sensor: https://www.sparkfun.com/products/12636

From the sensor we got 3 values, x, y, and z. We used these equations to calculate the raw data to Gauss.

Magnetic Flux Density = sqrt(MagX2 + MagY2 + MagZ2)

Here are some raw sample data:
MagX MagY MagZ
1,100192267 0,993682669 -0,37018952
1,082125309 0,993133335 -0,372142705
1,066866054 0,994903409 -0,371532334
1,047517319 0,995818964 -0,373912778

Could this be caused by noise from the other components, or are we missing something crucial

Mag_data.png

Any electric currents or magnetic materials in the vicinity can affect magnetometer readings. Exhaust flames include moving charged particles, which could in principle affect readings as well.

Since the Earth’s magnetic field ranges from 0.25 to 0.65 Gauss depending on location, it appears that your magnetometer is not properly calibrated.

MEMS magnetometers can have internal sources of error (ferromagnetic pole pieces to concentrate field) and external sources of error (resistor and capacitor end-caps on the same PCB, steel nuts and bolts in the device, etc).

Magnetometers have to be calibrated to remove these systematic errors (remember the Earth's field is 10^-4T or so, very small compared to stray ferromagnets (iron saturates at 2T).

http://diydrones.com/profiles/blogs/advanced-hard-and-soft-iron-magnetometer-calibration-for-dummies

Hi, Do you have the information to graph, the mag field vs altitude? It would make more sense as it is in a rapidly moving and rising environment. How was it transported into the atmosphere?

Tom..... :)

jremington: Exhaust flames include moving charged particles, which could in principle affect readings as well.

No, because the charges are in balance in an electrically neutral gas unless there's an electric discharge through it. Strong magnetic fields can influence flames(*), but electrically neutral gasses don't produce fields.

(*) mainly due to paramagnetic oxygen species in the flame, apprarently