Index
encoder_zero_points az_zero, el_zero, dk_zero, [camera=?]
Specify the encoder angles at zero azimuth, elevation and deck angle.
- Arguments:
-
PointingOffset az
- The azimuth encoder angle that corresponds to zero azimuth,
measured in the direction of increasing azimuth.
PointingOffset el
- The elevation encoder angle that corresponds to zero elevation,
measured in the direction of increasing elevation.
PointingOffset dk
- The deck encoder angle that corresponds to the chosen zero
point of the deck axis, measured in the direction of
increasing deck angle.
- Optional Arguments:
-
Camera number
- The number of the associated optical pointing camera. If
this is omitted, the pointing model of the currently
selected camera is configured.
- Example:
- The following example tells the control system that when the
telescope is pointing north, the azimuth encoder actually reads
10.5 degrees. Also that when the telescope is pointing at zero
elevation that the elevation encoder reports an elevation of -4.3
degrees. And finally that when the deck encoder reads -50.0
degrees the deck angle should be considered to be zero.
encoder_zero_points 10.5, -4.3, -50.0
- Context:
- The angles at which azimuth and elevation encoders report zero
counts do not correspond to the zeroes of topocentric azimuth and
elevation. This is both because manually positioning the encoders
to arcsecond accuracy is virtually impossible, and because the
zero points will gradually change as the telescope base sinks and
other parts of the telescope relax. Instead these zero points are
deduced by offline software while fitting the pointing model of
the telescope, ready to be installed with the encoder_zero_points
command.
Note that after a reboot the control system will refuse to track
a source or slew the telescope until this command has been
called, so this should be done from the
$CBI_DIR/conf/rtc.init
boot script.
Martin Shepherd (23-Jan-1999)