2
PREPARATION
2-8. Face-1/Face-2 Measurement
Face-1 Measurement: Measurements made with the vertical circle positioned to
the left of the telescope eyepiece
Face-2 Measurement: Measurements made with the vertical circle positioned to
the right of the telescope eyepiece
NOTE • Be careful not to catch your finger in the opening between the
instrument’s standard and the telescope when rotating the telescope.
• Mechanical constant error (except a few errors such as vertical axis error) can be
effectively cancelled out by averaging the values in Face-1 and Face-2.
Face-2 measurement Face-1 measurement
2-14
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