Tracking the geographic location of an animal

A tracking device comprising:

• a vector magnetometer to generate an output descriptive of direction of a magnetic field to which the tracking device is subject at a collection of different times;
• a longitude sensor to generate an output descriptive of a longitude position of the tracking device at the collection of different times, wherein the longitude sensor comprises a photodetector and is to generate the output descriptive of the longitude position based on illumination detected by the photodetector;
• and
• a data store to store one or more of a) the descriptions output by the vector magnetometer and the longitude sensor and b) a description of the geographic position of the tracking device,
• wherein the one or more of the description output by the vector magnetometer, the description output by the longitude sensor, and the description of the geographic position of the tracking device is timed so that a time to which the description is relevant can be determined,
• wherein at least some of the description output by the vector magnetometer and at least some of the description output by the longitude sensor are relevant to a same first time, and
• wherein the description of the geographic position can be determined based at least in part on the descriptions output by the vector magnetometer and the longitude sensor.

A tracking device comprising:

• a first means for generating an output descriptive of inclination of a magnetic field to which the tracking device is subject at a collection of different times;
• a second means for generating an output descriptive of a longitude position of the tracking device at the collection of different times, wherein the second means comprises a means for detecting illumination and is to generate the output descriptive of the longitude position based on illumination detected by the photodetector;
• and
• a means for outputting from the tracking device one or more of a) information descriptive of the outputs descriptive of the inclination of the magnetic field and the longitude position and b) a description of the geographic position of the tracking device,
• wherein the description of the geographic position can be determined based at least in part on the outputs descriptive of the inclination of the magnetic field and the longitude position,
• wherein the one or more of the output descriptive of the inclination of the magnetic field, the output descriptive of the longitude position, and the description of the geographic position of the tracking device is timed, and
• wherein at least some of the output descriptive of the inclination of the magnetic field and at least some of the output descriptive of the longitude position are relevant to a same first time.

A tracking device comprising:

• a magnetometer to generate an output descriptive of a magnetic field to which the tracking device is subject at a collection of different times;
• an alignment sensor, the alignment sensor to generate an output descriptive of an alignment of the magnetometer relative to gravity
• a longitude sensor to generate an output descriptive of a longitude position of the tracking device at the collection of different times;
• and
• a data store to store one or more of a) the descriptions output by the magnetometer, the longitude sensor, and the alignment sensor, b) a description of direction of the magnetic field and the description output by the longitude sensor, and c) a description of the geographic position of the tracking device,
• wherein the one or more of the description output by the magnetometer, the description output by the longitude sensor, the description output by the alignment sensor, the description of the direction, and the description of the geographic position of the tracking device is timed so that a time to which the description is relevant can be determined,
• wherein at least some of the description output by the magnetometer, at least some of the description output by the longitude sensor, and at least some of the description output by the alignment sensor are relevant to a same first time, and
• wherein the description of the geographic position can be determined based at least in part on the descriptions output by the magnetometer, the longitude sensor, and the alignment sensor.