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TRUE POLE ALIGNMENT of an
OBSERVATORY CLASS EQUATORIAL

3)

Square Optical Axis to Declination Axis

i) Align the telescope circle following (East of Pier), upon an equatorial star at culmination and record the sidereal time and hour angle.

ii) Reverse the telescope, circle preceding (West of Pier), and repeat.

iii) If angle S is less than a right angle, the star will be seen to transit late circle following and early circle preceding, and vice versa.

iv) The HA difference, less the sidereal time interval and 12hrs., gives twice the error.

i.e.

IMAGE imgs/TRUE_POLE_ALIGNMENT01.jpg

v) Convert the time error to arc and apply the correction by either shimming the saddle or adjusting the compound saddle push-pull bolts if the mounting has such a
feature.

vi) Repeat the procedure and note the residual error.