43
V
CHECKI
NG AN
D ADJ
USTMENT
4. Vertical Circle Zero Point Error
1) Checking
(1) Set-up the instrument on the tripod and perform leveling.
(2) With the telescope in the face-1 position, aim at an arbitrary Target P
positioned within ±10°/±11G from the horizontal plane, and take a
reading of the vertical angle...VR
(3) Reverse the telescope to the face-2 position and take another reading
of target P’s vertical angle...VL
(4) If VR + VL = 360°/400G when the zenith angle is set to 0°, or if VR +
VL = 180°/200G (or 540°/600G) when the horizontal angle is set to 0°,
no adjustment will be necessary. Otherwise, refer to the following
adjustment procedure.
Vertical error (2·e) corresponds to the above angles (360°, 180°, &
540° or 400G, 200G, & 600G), and is referred to as the vertical
constant. The vertical constant is compensated for by doubling the
zero point error (e) in the following procedure. Note that compass
scale error (2·e) is not related to the vertical constant. Therefore,
take a reading using either the zenith 0° or horizontal 0°, and check for
error.
Summary of Contents for NE-100
Page 48: ...V CHECKING AND ADJUSTMENT ...
