VARIATION for the current day.
Used in navigation with a magnetic compass.
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Variation is the angle between the magnetic and geographic meridians at any place, expressed in degrees east or west to indicate the direction of magnetic north from true north. Called MAGNETIC VARIATION when a distinction is needed to prevent possible ambiguity. Also called MAGNETIC DECLINATION. (Bowditch)

The app uses the World Magnetic Model: WMM2020.
The new model is valid from 10/12/ 2019 through 31/12/2024.
See: https://www.ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml

Your last position is automatically saved.
- Storage permission needed for Google Maps cache and for save your position.

COURSE CALCULATOR
Compass and true course.
DEVIATION COEFFICIENTS
Dev = A + B SIN(Ra) + C COS(Ra) + D SIN(2Ra) + E COS(2Ra)
Calculate the coefficients A,B,C,D,E with "Magnetic compass" Windows application, (available at Navigational Algorithms website).
Enter them and save. The App will read the data and Course calculator will be able to compute the deviation.


USER INTERACE
- Zoom buttons +/-
- Map types: normal, terrain and satellite
- GPS location. ("Location" App permission must be allowed. Switch on you GPS, and then automatic location detection is possible)

Events on Map:
• Long Click: adds a mark with the variation at position for the current day.
• Tap the Mark to see the information.
• Map gestures: https://developers.google.com/maps/documentation/android-sdk/controls