astrocompass การใช้

Because of this procedure, an astrocompass requires its user to be in possession of a nautical almanac or similar astronomical tables, one of its chief disadvantages.
In its most basic form, the astrocompass consists of a base plate marked with the points of the compass, with a mechanism known as an equatorial drum mounted on it.
Once all these settings have been made, the astrocompass is simply turned until the astronomical body is visible in the sights : it will then be precisely aligned to the points of the compass.
GPS and other similar forms of electronic navigation aids mean that the astrocompass is now functionally obsolete anywhere except for areas very close to the poles where GPS coverage is not available and there are no current electronic navigation aids.
Thus, with knowledge of the current time and geographical position in the form of latitude and longitude, which are set on the instrument using dials, an astrocompass can be sighted on to any astronomical object with a known position to give an extremely accurate reading.