I didn't know about that...

[stellar_muddle]

For future reference and investigation:
Considerations on The Viking Sun Compass
VIKING SUN COMPASS
Bearing dial, sunstone, sunsticks
Bearing dials - looks like over-eager extrapolation there though...
Check for originals in National Museum of Denmark and slightly more scholarly references...

Must stop procrastinating - very minorly astronomically related.

Recalibration awaits...