LAPOD 2.0 - Latin American Paleomagnetism Online Database

Sun declination

Sun-compass calculation for paleomagnetic field orientation

Observation data

Enter the sun azimuth measured with the field compass, the observation date and local civil time, site coordinates, and UTC offset.

D_sun = wrap_±180°(A_{true Sun} − A_{measured Sun})

Azimuths are clockwise from north. Longitude is positive east. UTC offset is local time minus UTC (e.g., Mexico City standard time = −6). Positive Dsun is east and negative Dsun is west.

Select .txt, .csv or .tsv file

The file is processed locally in your browser.

Recommended columnsID, Lat, Lon, Date, Hour, Minute, UTCOffset, SunAzimuthDate format: YYYY-MM-DD. Example: S1,20.70,-100.45,2026-03-21,10,35,-6,128.4

Calculated results

Solar declination δ is astronomical; Dsun is the magnetic declination derived from the sun-compass observation.

No observations calculated yet.

Results plots

Measured and calculated true solar azimuth

Sun-derived magnetic declination

Astronomical solar declination

Calculation notes

The solar position is calculated from Julian time using standard solar ephemeris equations, including the equation of time and the local solar hour angle. The true solar azimuth is measured clockwise from geographic north.

For paleomagnetic use, the measured azimuth is assumed to be a compass bearing toward the Sun. If your field measurement is the shadow azimuth, add 180° (and normalize to 0–360°) before entering it.