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Methods for Astronomical Observation
Traditional Methods for Astronomical Observation
Currently, astronomical observation usually adopts the traditional methods, mainly
to determine time by receiving time signals emitted from the observatory and to
record time by a chronometer. The instruments used in observations are primarily a
Wild T4 theodolite and a 60
astrolabe, and the methods extensively applied are as
follows:
1. The Wild T4 theodolite allows determination of the first-order astronomical
latitude by applying Talcott's method.
2. The Wild T4 theodolite allows determination of the errors of a timepiece (time
corrections) by the method of equal altitudes of two stars, one east and the other
west of the meridian (Zinger's method), in order to determine the first-order
astronomical longitude.
3. The hour angle of Polaris is applied for determining the astronomical azimuth.
4. A 60
astrolabe (composed of T3 and 60
prisms) allows simultaneous determi-
nation of the astronomical longitude and latitude of the second, third, and higher
orders using the method of equal altitudes of multiple stars.
New Methods for Astronomical Measurement
The new methods primarily employ the GPS OEM (Original Equipment
Manufacturer) board with time transfer service to receive satellite signals. Elec-
tronic theodolites are adopted for observation instead of optical theodolites; porta-
ble computers with advanced programming are used to replace the chronometer and
timepiece for time comparison and timekeeping; and the autonomous recording and
calculation of the observational data are also enabled. The currently adopted
methods are as follows:
1. Use the method of observing multiple stars at approximately equal altitudes to
determine the first- and second-order astronomical
longitude and latitude
simultaneously.
2. Carry out repeated observation using the method of hour angle of Polaris to
determine the first- and second-order astronomical azimuth.
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