Paramount ME User’s Guide
37
What Is AutoHoming?
AutoHoming is an automated initialization process that slews both the right ascension and
declination axes to a mechanically fixed position called the home position. The control
system must perform this step every time the Paramount ME is turned on to reestablish the
mount’s absolute position to the nearest one arcsecond.
The home position in the northern hemisphere is located at
approximately hour angle 2 and 0 degrees declination. The home
position is a fixed, mechanical orientation and cannot be changed; it is
defined by the physical position of the gears relative to internal
homing sensors. If the mount is not physically pointing to
approximately hour angle 2 and 0 degrees declination after the home
position is located, then either the Versa-Plate is mounted incorrectly
(page X44X), or the mount’s right ascension axis is not aligned north-
south. If the coordinates of the telescope cross hair in TheSky6 show
a different position after homing, then TheSky6’s time or sync
information is incorrect (page X82X).
The Paramount ME will not slew or track until the
mount is successfully homed.
When the mount is homed, it slews to the home position and sets the control system’s
“position registers” to zero. When star synchronization is performed, the hour angle and
declination of the home indexes are stored in the internal flash of the Paramount ME’s
control system. Subsequent sessions simply use the local sidereal time, as computed by
TheSky6 Professional Edition, to accurately determine the mount’s equatorial coordinates.
Make sure TheSky6’s time is accurate (see page X53X).
Homing provides the following benefits.
Once a mount is aligned with the celestial pole and homed, extremely repeatable
and accurate pointing can be achieved using TheSky6 Professional Edition and the
TPoint Telescope Pointing Analysis software.
After homing, the mount “knows” its orientation and therefore cannot be slewed into
the pier. The right ascension limits are approximately 5 degrees past the meridian
in each direction (east and west) and in declination the limit is approximately –90
degrees declination.
The periodic error correction (PEC) function uses this information to calibrate the
control system’s internal PEC table with the orientation of the worm gear.
You can quickly recover from power outages or other communication malfunctions.
Homing the Mount Using the Joystick
To home the mount using the joystick, make sure the mount is powered, and the
servomotors are initialized (see page X35X), then deliberately tap the button on top of the
joystick handle twice. If you move the joystick during the homing procedure, the mount
stops slewing and homing is aborted. Left-right motion causes the RA axis to stop slewing;
forward or backward motion causes the declination axis to stop slewing (see XFigure 18X).
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