Parking the Mount

Parking the Mount

Before powering down the mount, it is desirable to return the mount to a known position (a park position).

If you have set some mount RA limits, parking the mount properly before power down is essential in order to record the limits for the next power up. It will also be important for restoration of stored alignment data.

You have basically 2 options for parking:

  • the home position
  • a customized position very useful for installations where a roof of an observatory would not clear the telescope upon close-up. A common customized park position is with the balance/counter-weight bar horizontal and the telescope itself horizontal.


You should park only if the alignment is complete. Do not park an unaligned scope or you will be unparking using invalid data creating an invalid alignment table.

Background information about parking and bootup

EQMOD gets the equatorial coordinate values (RA and Dec) from the mount itself. If you disconnect the driver while maintaining power to the mount and then re-activate the EQMOD driver, it will continue to operate based on the RA and Dec values stored in the mount's stepper controller. This means that even if you shutdown the PC but leave the mount in a tracking state and then reconnect EQMOD, it will continue to display and report the correct RA and Dec values based on the current position of the mount.

The setup will revert to a home position only if you remove and re-apply the power to the mount. When EQMOD reconnects it will know if the mount was reset or was left in a tracking state.

To allow continuity of operation after a power recycle, the mount has to be parked at a known position (either the home position or a custom park position). When the mount is parked the last RA and Dec values are recorded. Upon mount power up, EQMOD restores the RA and Dec values to the mount. This works successfully based on the assumption that the worm gears remain at the same position as when the mount was shutdown.

Assuming the mount is parked at the end of a session and unpark is performed on mount bootup, and assuming the N‑Point data is saved and restored, GOTO's will remain accurate even if you use the last N‑Point list. Sync data will also remain correct and accurate. Of course, the PC time and coordinate values need to be accurate. Using a GS module to set the correct time in your computer clock as well as EQMOD will make restores of stored N-Point data work correctly.

/home/welshdra/public_html/eqmod/data/pages/parking_the_mount.txt · Last modified: 2009/05/22 14:00 (external edit)
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