(1) 
a differential refraction correction due to the fact 
that the satellite is not, like the stars, at infinity, 
(2) a parallactic angle for eccentricity of the aiming 
direction because the location of the photographed 
mirror image of the sun, reflected from the surface 
of the balloon satellite, depends on the relative 
positions of sun, satellite and observation station, 
and, in general, does not correspond to a direction 
aiming towards the center of the balloon, and 
(3) a light travel time correction, which is necessary 
because of earth rotation, the amount of which is 
different for different observing stations because 
of the varying distances between satellite and 
individual observing stations. 
Finally, a significant reduction of the scintillation 
effect is obtained by statistical integration. Fifth and 
third degree polynomials, respectively, are fitted to all 
observed satellite images in terms of their x (along the 
path) and y (transverse) coordinates, thus ultimately express 
ing the fictitious satellite image coordinates as functions 
of time. With an interpolation procedure which, again, must 
take into account light travel time, the final image coordinates 
together with their covariance matrix, are computed for a 
selected number of satellite positions. These coordinates 
comprise the input material for the final spatial triangulation 
of the station coordinates. 
These coordinates simulate image positions which would 
have been obtained if 
(1) the photogrammetric camera had formed the images 
according to the principle of central perspective, 
(2) the comparator had no linear scale errors and its 
x and y movements no deviation from perpendicularity, 
(3) the origin of the image coordinate system coincided 
with the principal point, 
(4) the photography had been executed in vacuo, in 
other words, in the absence of refraction and 
scintillation, 
(J) the images originated from the center of the balloon 
satellite, 
(6) both earth and satellite were stationary and, con 
sequently, no aberrations or light travel time 
influence existed,