Mount Parameters

 

Select the type of mount you are using.  Select Fork Mount for any type of mount that can track and slew constantly through the meridian.  Select German Equatorial Mount for any type of mount that requires a "flip" at the meridian.

 

The Delay after slew entry tells CCD Commander to wait an additional period of time after the slew completes.  This is useful if a dome needs extra time to catch up to the mount movement.

 

The Disable Guide Declination Compensation will cause the Declination setting in CCDSoft or MaxIm to be set to 0 while autoguiding.  This will disable any declination compensation to the guide star corrections.

 

The GEM Setup box contains additional parameters for German Equatorial Mounts.

 

The Eastern Limit and Western Limit values are very important and tell CCD Commander when a slew will send the mount to the eastern or western side.  

 

The easiest way I have found to determine the Eastern Limit and Western Limit is as follows:

  1. Position the mount with the telescope on the East side of the mount, looking at the Western sky.

  2. Slew to a target just East of the meridian (it helps to use a planetarium to determine a target).

  3. If your mount flips, then your Eastern Limit will be 0 (or very close to it).  Skip to Step 7.

  4. If your mount does not flip, pick another target slightly further East.  Slew to this target.

  5. Repeat step 4 until your mount flips.  Your Eastern Limit will be the difference between the target RA and the Local Sidereal Time.  (Eastern Limit must be 0 or positive.)

  6. Now position the mount with the telescope on the West side of the mount, looking at the Eastern sky.

  7. Slew to a target just West of the meridian.

  8. If you mount flips, then your minimum Western Limit is 0.

  9. If your mount does not flip, pick another target slightly further West.  Slew to this target.

  10. Repeat step 9 until your mount flips.  Your minimum Western Limit will be the difference between the target RA and the Local Sidereal Time.  (Western Limit must be 0 or positive.)

 

The Western Limit serves a second purpose - telling CCD Commander how far past the meridian you can track.  Some mounts will come up with a value of 0 for the Western Limit using the above procedure, but the Western Limit could be larger.  Now with your telescope on the West side of the mount, slew your telescope until it hits its safety limit (or just before it hits the tripod/pier).  Determine the RA your telescope is looking at.  Now determine the difference between the telescope RA and the Local Sidereal Time.  This is your maximum Western Limit.

 

You should set the Western Limit value anywhere between the minimum value determined in steps 8-10 above, and the maximum value.

 

When you start an action by pushing the Start Action button on the main window, CCD Commander needs to determine what side of the mount your telescope is on.  Normally this determination is easy.  However, if the telescope is in the zone defined by the Eastern Limit and Western Limit values, it can be on either side of the mount.  CCD Commander needs to determine which side of the mount the telescope is on for proper operation.  When Automatically determine mount side at start-up is checked, CCD Commander will slew the telescope to force it to one side or the other.  CCD Commander will always slew the telescope to the "normal" side of the mount given where it is pointing.  If the telescope is looking to the eastern sky, CCD Commander will force the telescope to the west side of the mount.  If the telescope is looking to the western sky, CCD Commander ill force the telescope to the east side of the mount.

 

Unchecking Automatically determine mount side at start-up check box allows you to specify the mount side at startup when the telescope is in the "overlap" zone defined by the Eastern Limit and Western Limit values.  The following window will be shown when the telescope is in the "overlap" zone.

 

 

You must specify the correct side of the mount that the telescope is on.  Alternately, you can allow the automatic procedure, described above, to force the mount to one side automatically.

 

The next selection tells CCD Commander which side of the meridian the autoguider was calibrated on.  This selection also applies to the angles in the Rotator tab.  It is very important for all of these values to be calibrated/computed on the same side of the meridian.

 

The Enable Slew Scripts check box allows you to specify a custom script to run before any mount movement and after any mount movement.  This can be very useful for dome users that do not want the dome to rotate until the mount has finished moving.  Once you check this box you can select the scripts by clicking the "..." buttons.

 

Note: The Park Mount action only executes the Before Slew script.

 

When Verify telescope coordinates after Move To action is checked, CCD Commander will query the telescope coordinates at the end of the slew and compare them to the Right Ascension and Declination that the telescope was supposed to slew to.  Occasionally a minor error can prevent the telescope from reaching its desired coordinates, and this will trap those conditions.  When the coordinates do not match, CCD Commander will slew to your target a second time.  If the slew fails again, CCD Commander will skip ahead to the new Move To action in your list.

 

Maximum acceptable telescope pointing error specifies how close the telescope coordinates must be to the target Right Ascension and Declination in the above verification.  If you are using a pointing corrector such as TPoint, you might need to increase this value.  TPoint adjusts the telescope pointing to put it properly on target, but doesn't adjust the telescope reported coordinates.  Thus the telescope can report coordinates off target, yet still be pointing at the proper location.

 

It is recommended to leave the Verify telescope coordinates after Move To action enabled with the default Maximum acceptable telescope pointing error unless you experience problems with these settings.  When you have slew failures due to the coordinates not matching, first try to increase the Maximum acceptable telescope pointing error to a value specific to your mount.