EQASCOM PolarScope Alignment Tool

EQASCOM PolarScope Alignment Tool

Important:

For the following procedure work properly, you must be sure the the reticule on the mount is correctly centred. The manufacturer's manual outlines the required procedure. (Typically you just centre the 'X' of the polarscope on a distant object (in daylight) and rotate the mount 180d. The object should stay centred under the 'X“. If not, use the appropriate set screws to move the reticle.)

The alignment of the reticle is not important (although the manual describes how to do it) as the following procedure works with the existing alignment of the reticle. In other words, it doesn't matter how the reticle is rotated on the axis. The only requirement is that it is centred. On the other hand, if you have equipment on the mount, you may wish to disassemble the polarscope and rotate the reticle so that the mount can be rotated into the required positions with the mounted equipment.

You also need 1.16b of EQMOD (or later) for this feature.

Initial Set-up Procedure:

  • Set up the mount in the HOME position i.e. counterweight shaft down. You may want to mark this position on you mount in some way to ensure accurate and consistent setup between sessions. Some folks use bubble levels for this purpose. Rotate the Mount in RA and using a bubble level lock the clutch when the counterweight shaft is horizontal. Set the RA setting circle so that the indicator reads 0. Unlock and rotate the RA Axis until the setting circle reads 6 (i.e ¼ turn).
  • Power up and connect to EQMOD.
  • Disable limits (if enabled). Caution: If you have equipment mounted, you should be aware that the mount may move in a way that could cause the 'scope to hit the pier. Monitor the movement of the mount carefully. The following instructions assume there's no equipment attached to the mount.
  • UNPARK.
  • Use EQMOD slew controls to move the mount in DEC (so the polar scope has a clear view) and in RA to move the Pole Star marker to the “6 o'clock” position (straight down as viewed through the polarscope). (Note: You can use the 12 o'clock position if you wish).

  • The easiest way to do this is to first adjust the mounts Alt/Az bolts to get the Pole Star centred in the reticule.

  • Now Adjust the mounts Altitude bolt until the Pole Star moves downwards (or upwards) to intercept the circle.

  • Now slew the mount in RA until the Pole Star indicator (the little circle) is superimposed over the Pole Star

  • Click on the Pole Star HA button (it's the button that shows Polaris HA time). To bring up the PolarScope View window. You will note the drop down that selects either 6 o'clock or 12 o'clock positions. Choose according to your setup.
  • Click on the [Align PolarScope] button, which will cause the mount to slew in RA to correctly position the Pole Star marker. Very Important: Monitor the movement of the mount to ensure there are no unexpected collisions.
  • Click on the [Set PolarScope Home] button to record this position in the EQMOD parameter file.
  • Adjust the mount using the Alt and Az bolts so that the Pole Star is in the little circle. This completes polar alignment.
  • PARK the mount back to HOME and re-enable limits (if required).
  • Put the OTA, weights etc. onto the mount, UNPARK and carry out goto alignment as usual.
  • At the end of the session PARK the mount and power down.

Subsequent Set-up Procedure:

Note: Any manual movement of the RA axis will invalidate a stored polar scope home position. In other words, you will need to reestablish the polar home position as outlined previously before you use the polarscope alignment tool.

  • Set up the mount in the HOME position i.e. weights down
  • Power up and connect to EQMOD.
  • Disable limits, UNPARK.
  • Click on the [Move To PolarScope Home] button. The mount will slew in DEC so the polarscope can be used and in RA to place the Pole Star marker at the 6 o'clock position.
  • Click on the [Align PolarScope] button. The mount will slew in RA to correctly position the Pole Star marker.
  • Adjust the mount using the Alt and Az bolts so that the Pole Star is in the little circle. This completes polar alignment.
  • PARK the mount back to HOME and re-enable limits if required.
  • Put the OTA, weights etc. onto the mount, UNPARK and carry out goto alignment as usual.
  • At the end of the session PARK the mount and power down.

Procedures without Park/Unpark.

For those folks who do not wish to use the PARK/UNPARK functionality of EQASCOM the polarscope alignment tool can still be used. There are two procedures you can use:

Procedure 1 (manual)

  • Set up the mount in the HOME position i.e. weights down.
  • Power up and connect to EQMOD.
  • Click on the Pole Star HA button. To bring up the PolarScope View window
  • Move the mount in DEC so the polar scope can be used and in RA so the Pole Star marker corresponds to the same position as shown in the PolarScope View window.
  • Adjust the mount using the Alt and Az bolts so that the Pole Star is in the little circle. This completes polar alignment.
  • Move the mount back to HOME.
  • Put the OTA, weights etc. onto the mount, and carry out goto alignment as usual.

Procedure 2 (semi-automatic)

  • Set up the mount in the HOME position i.e. weights down.
  • Power up and connect to EQMOD.
  • Disable limits (if enabled)
  • Move the mount in DEC so the polar scope can be used and in RA to move the Pole Star marker to the 6 o'clock position.

  • Click on the Pole Star HA button. To bring up the PolarScope View window
  • Click on the [Align PolarScope] button, which will cause the mount to slew in RA to correctly position the Pole Star marker.
  • Adjust the mount using the Alt and Az bolts so that the Pole Star is in the little circle. This completes polar alignment.
  • Move the mount back to HOME, re-enable limits (if required). 9. Put the OTA, weights etc. onto the mount, and carry out goto alignment as usual.

Southern Hemisphere Use

The right ascension coordinate of the pole star is read from the EQMOD.ini file (located in the %APPDATA%/EQMOD folder). Edit this file and you will find an entry as follows:

POLE_STAR_RA=2.5302

For Southern Hemisphere use you will need to change this value to correspond to one of the Octans stars that appear in the asterism shown on the polarscope reticule. The polarscope home position would then be when that star is in the “six o'clock” position.

For example using Chi Octans the ini file would be changed to POLE_STAR_RA=1 8.98

And the “home ” position for the polarscope alignment tool would be:

/home/welshdra/public_html/eqmod/data/pages/eqascom_polarscope_alignment_tool.txt · Last modified: 2010/05/26 18:35 (external edit)
 
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