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lead us, however, into the domain of geodesy proper. In pur 
suing the purpose of this presentation the emphasis is on 
the analysis of such photogrammetric operations and results 
which reflect into the general area of precision photogrammetry. 
1. The Method of Photogrammetric Satellite Triangulation 
The geometric principle of photogrammetrie satellite 
triangulation can he explained in several ways. Similarly, 
depending on the professional background of the experimenter, 
the data acquisition method as well as the mathematical 
formulation of the data reduction procedure will differ. Most 
obvious is the difference in approach between the astronomer 
and the photogrammetrist. The astronomer is inclined to favor 
rather long focal length in order to increase the precision 
by scale at the expense of the geometric strength inherent 
in wider viewing angles. Haunted by his experience with the 
problem of "seeing" the astronomer favors observational systems 
which track, more or less exactly, the motion of the object 
to be photographed, in order to make possible rather long 
exposure times, thus integrating the image forming process in 
order to reduce the scintillation effect. The astronomer applies 
predominantly a data reduction process in which the interpola 
tion of the unknown target image (satellite) into the reference 
frame (known stars) is obtained by the so-called plate con 
stant method. This is essentially a fractional linear trans 
formation augmented with higher order terms, the free variables 
of the solution being coefficients whose precise physical 
meaning in terms of instrumental constants and geometrically- 
defined orientation elements remain obscured. 
The photogrammetrist--as well as the geodesist--is more 
likely to favor fixed cameras because of his concern about 
the stability and control of tracking instrumentation, 
especially in programs requiring extended field operations 
under conditions far removed from the astronomical observatory 
environment. Particularly the photogrammetrist is inclined 
to sacrifice some focal length to gain increased geometrical 
strength from a correspondingly wider bundle. Certainly he 
is sold on the need to introduce into the data reduction pro 
cedure mathematical models which simulate the photographic 
recording process by parameters with distinct geometrical and 
physical meaning. In principle the mathematical formulation 
for the reduction of photogrammetric satellite triangulation 
is the same as for aerial triangulation, or for any three- 
dimensional triangulation scheme based on- photogrammetric raw 
data. 
The reduction consequently is based on the condition 
of collinearity, expressed by a simple transformation relating