1. What is Magnetic Declination?

Magnetic declination is the angle between magnetic north (the direction the compass needle points) and true north. This angle varies depending on your location and changes over time due to shifts in Earth's magnetic field.

2. How Does the Calculator Work?

The calculator uses the Australia-specific geomagnetic model:

Where:

• Latitude — Geographic coordinate (-90° to 90°)
• Longitude — Geographic coordinate (-180° to 180°)
• Date — Current date (for secular variation)

Explanation: The AUS model calculates magnetic field components based on spherical harmonic coefficients that are specific to the Australian region.

3. Importance of Magnetic Declination

Details: Accurate declination values are crucial for navigation, surveying, and any activity requiring precise orientation. In Australia, declination values range from positive (east) to negative (west) depending on location.

4. Using the Calculator

Tips: Enter coordinates in decimal degrees (e.g., -33.8688, 151.2093 for Sydney). The date accounts for the secular variation of Earth's magnetic field.

5. Frequently Asked Questions (FAQ)

Q1: Why is the Australian model different?
A: Australia has unique geomagnetic characteristics due to its location relative to Earth's magnetic poles, requiring a region-specific model for better accuracy.

Q2: How often does declination change?
A: Declination changes gradually over time (secular variation), typically a few minutes per year, but this varies by location.

Q3: What's the typical declination range in Australia?
A: Currently ranges from about +12° in the west to -15° in the east, varying by location.

Q4: How accurate is this calculator?
A: Using the official AUS model, accuracy is typically within 0.5° for recent dates.

Q5: When would I need this information?
A: Essential for navigation, map reading, surveying, orienteering, and any activity requiring precise directional information.