The simplest way to set Home sensor position (after it is calibrated) is to redirect it to the north
manually and enter value:
HomeSensorPosition = 360 ° - the current position of the dome,
to the Home Sensor Position field.
Home sensor position can be also determined in three ways:
1. Protractor and compass
First, simply by measuring the angle between the north and the sensor direction. Due to the low
accuracy of the compass, this method can not be too precise.
2. Ruler and compass
Second, by using the Pythagorean right. By measuring the sides (lenght) of the triangle the angle
can be calculated. However, in this method, we must use the compass again to state the north
and the precision of measurements will determine the accuracy of our calculations.
3. Telescope
Using the accurate sky atlas we can determine the angle that interests us with high precision. We
will need a telescope with GoTo support, a long pointer and the sky atlas.
1. In the Dome Geometry configuration panel all values have to be set to zero except the
dome’s radius value
3. Paste the adhesive tape horizontally on the dome’s shutter and indicate its center
4. Mount the pointer parallel to the telescope’s optical axis so that its end was as close
as
possible to the adhesive tape.
5. Synchronize the telescope with the sky (alignment)
6. Direct the telescope to the celestial North Pole using GoTo
7. As precisely as possible set the dome in such way the pointer attached to the telescope
shows the shutter’s center
8. Enter the value:
HomeSensorPosition = 360 °-the current position of the dome
in the HomeSensorPosition box
9. Re-enter previously cleared fields in the Dome Geometry panel
10. Close the configuration window
11. Save somewhere (for the future) values stored in the Home Position field.
And that's all – we have just set the Home sensor position with the dome’s encoder accuracy. It is
worth to save and remember it, in case you accidentally change these values. The dome’s
azimuth is estimated on those values base.
The accuracy of this method is based on the fact that the telescope with the pointer becomes a
compass, with needle of 1.5m length. Millimeter accuracy when selecting a center of the shutter
allows to indicate north with accuracy of less than one minute of arc. Using the laser pointer, you
will be able to set the north direction even more precise. Determine shutter’s center using a
plump bob.
Note: Home and Park positions are saved in the form of a decimal of the angle expressed in
degrees.
