#ha_error value sec value mm
#az_error value sec value mm
#zd_error value sec value mmh value mmv
These define the default error in seconds for subsequent horizontal angle, zenith distance, and azimuth data. Projection bearings are assigned the same errors as azimuth data. For horizontal angles and azimuths this may include a mm component, representing a plumbing error in millimetres. For zenith distances the error may include a mmh component representing the plumbing error, and an mmv component representing the instrument/target heighting error. This will be converted to an angle errors based on the length on the line. The observation error is calculated as the root sum of squares of the components. Note that SNAP calculates the length of the line based on the coordinates when the observations are loaded - they do not get updated when the coordinates are changed at each iteration. You need to run SNAP again with the new coordinates to recalculate the errors.