STAR*NET V6 - Circe

APPENDIX C – ADDITIONAL TECHNICAL INFORMATION
For reference, some general information and formulas used are listed here.
C.1 Program Limits
Limits for input data used in the program:
Number of stations in a network: 10,000
Length of an input data line: 500 Characters
Length of station names: 15
Length of station descriptors: 48
Length of instrument library names: 15
Limits for data in the STAR6.CUS custom grid and linear units definitions file:
Length of a data line: 128 Characters
Length of an ellipsoid name: 18
Length of a zone name: 18
Length of a linear “units” name: 8
Limits for data in the STAR6.FMT format definitions file:
Length of data line: 154 Characters
Length of format style name: 22
Length of format script definition: 128
C.2 Refraction
The formula used in the STAR*NET to compute the internal refraction correction to
zenith angles is shown in section 3.20, page 264, “Geodesy,” by G. Bomford, Oxford
University Press, 1971. This formula states that:
Refraction Correction = Coefficient of Refraction * Central Angle
Where: Central Angle is the angle subtended by the observation line at the earth’s center.
When the program is first installed, a default coefficient value of 0.07 is initialized in the
company options. This is considered an average value that can be used for most average
field conditions. However, in the publication, Bomford indicates in Table 1.1 on page 59
that coefficients may vary in extreme cases from “0.81” (about 10 meters above bare
plains, night, still and clear) to “-0.10” (about 10 meters above bare plains, midday, still
and clear, probably with some heat mirage). In the latter case, with a negative coefficient
of refraction, the refraction path would bend toward the ground rather than upward.
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